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Recent problems solved by 'RAY100'
RAY100 answered: 1636 problems
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logarithm/201699: x^2 + 2^x = 101 1 solutions
Answer 151978 by RAY100(1637) on 2009-07-01 13:59:27 (Show Source):
You can put this solution on YOUR website!x= 6.017,,,,,by trial and error,,,assume x,,,calc eqn
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check,,,6.017^2 +2^6.017=100.963 = 101
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Equations/201700: multiply (x+2)(x-3)(x+4) 1 solutions
Answer 151975 by RAY100(1637) on 2009-07-01 13:40:42 (Show Source):
You can put this solution on YOUR website!(x+2)(x-3)(x+4)
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use FOIL first
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(x+2) ( x^2 +4x -3x -12)
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(x+2) ( x^2 + 1x -12)
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now use distribution
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x(x^2 +x -12) +2 ( x^2 +x -12)
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x^3 +x^2 -12x +2x^2 +2x -24
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x^3 +3x^2 -10x -24
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checking,,,if x=0,,, original and answer = -24,,ok
if x=1,,,both = -30,,,ok
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Travel_Word_Problems/201710: If a race car can go around a track in 5 minutes,then how long will it take to go around the track if it increases its speed by 20%? 1 solutions
Answer 151971 by RAY100(1637) on 2009-07-01 13:14:42 (Show Source):
You can put this solution on YOUR website!v=d/t
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(1) v=d/5
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(2) 1.2 v = d/t
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from (2),,v=d/(1.2 t) = d /5,,,,,,from(1)
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1.2 t =5
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t= 5/1.2 = 4.17 min
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checking,,,,let d=10, v= 10/5 =2
v2= 10/4.17 = 2.4
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2.4 / 2 = 1.2,,,or 20 % higher,,,ok
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Inequalities/201713: The daily number v to an amusement park was always at least 852but never more than 1153. How is this expressed in an inequality? 1 solutions
Answer 151968 by RAY100(1637) on 2009-07-01 12:54:25 (Show Source):
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Linear_Equations_And_Systems_Word_Problems/201703: sanjay is now 1/2 as old as his brother. In 6 more years he will be 3/5 as old as his brother. Find the present age of each boy. 1 solutions
Answer 151936 by RAY100(1637) on 2009-07-01 09:16:16 (Show Source):
You can put this solution on YOUR website!Let s = Sanjay age,,,b= Brother's age
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(1) s = (1/2) b
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(2) ( s+6) = (3/5) (b+6)
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subst (1) in (2)
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(1/2) b +6 = (3/5)b + 18/5
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6- 18/5 = (3/5 -1/2) b
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2.4 = .1 b
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24 = b,,,,,,s= 1/2 b = 1/2 *24 = 12
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check
(1) 12 = 1/2 * 24 ,,,,ok
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)2) 12 +6 = (3/5) ( 24 + 6 )
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18 = 3/5 *30 =18 ,,,,,,ok
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Angles/201706: find angle A if it supplements angle B which is equal to 70-x 1 solutions
Answer 151934 by RAY100(1637) on 2009-07-01 09:06:36 (Show Source):
You can put this solution on YOUR website!A + B = 180,,,,def supplementary
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B= (70-x),,,,given
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A +(70-x) =180
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A + (70-x) = 180
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A = 180 -70 +x
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A= 110 +x
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check, x=10, (70-x) =60,,,A=120,,,answer,,,110+10=120,,,,ok
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Equations/201409: Solve the inequality.
((3x)/(7-x)) > x
1 solutions
Answer 151921 by RAY100(1637) on 2009-06-30 23:34:26 (Show Source):
You can put this solution on YOUR website!(3x) /(7-x) > x
3x > x(7-x)
3x> 7x -x^2
0> -x^2 +4x
0> x(-x +4)
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x<0,,,,x>4
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check ,,x<0,,use x=-1, -3/8 > -1,,,,,ok
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0less than x less than 4,,use x= 1,,,3/6>1,,,,,,not true
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x>4,,,use x=5,,,15/2 > 5,,,,,ok
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therefore ,,,x<0,,,x>4
.
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Exponential-and-logarithmic-functions/201660: This question is from textbook
log(square root of 1-x) - log(square root of x+2)=logx
First I sqared both sides and got log 1-x -log x+2=log x squared
then i performed the quotient property of logs and got log(1-x/x+2)=log x squared then I got 1-x =x squared (x-2) then I got X cubed - 2x+ x-1=0 1 solutions
Answer 151918 by RAY100(1637) on 2009-06-30 23:12:03 (Show Source):
You can put this solution on YOUR website!Good work,,,,but watch signs for last 2 steps
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log{ (1-x) / (x+2) } = log (x^2)
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(1-x) / (x+2) = x^2
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(1-x) = (x^2) (x+2)
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1-x = x^3 + 2x^2
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0 = x^3 +2x^2 +x -1
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Polynomials-and-rational-expressions/201489: Simplify
3^wtimes3^5^-wtimes3
thank you 1 solutions
Answer 151914 by RAY100(1637) on 2009-06-30 22:54:02 (Show Source):
You can put this solution on YOUR website!3^w * 3^5^-w *3^1
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3^w * 3^(-5w) *3^1
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3^(w -5w +1)
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3^(-4w+1)
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check, w=o, original and answer = 3
w=1,,both = 1/3^3
w=2,,both = 1/3^7,,,,ok
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Geometry_Word_Problems/201641: How do I figure out the diagonal measurments of a square? 1 solutions
Answer 151881 by RAY100(1637) on 2009-06-30 16:59:55 (Show Source):
You can put this solution on YOUR website!(1) diagon separates a square into 2 equal triangles. legs = "s",,
diagonal =d,,,,as it is a right triangle(square corner),,
use pythagorous,,c^2 = a^2 +b^2,,,with a = b =s,,,c=d,
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d^2 = s^2 +s^2 =2s^2,,,,d = sqrt 2 s^2 = s*sqrt2,,,,,
.
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or (2) recognize that the triangles are ,,,45-45-90, with side ratios,
1-1-sqrt2,,or s-s-s*sqrt2,,,and see d= s*sqrt2
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Quadratic_Equations/201636: Hi, Could you help me to find a way to this problem?!Tanks=)
One number is 6 less than a secound number.The product of the numbers is 48 more than the square of the smaller number.Find the two numbers.
I tryed to solve with this way but i couldnt finish it:



1 solutions
Answer 151879 by RAY100(1637) on 2009-06-30 16:52:43 (Show Source):
You can put this solution on YOUR website!(1) x =y-6,,,,,,x = smaller, y = larger
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(2) xy = 48 + x^2,,,,,product means multiply
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subst (1) in (2)
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y(y-6) = 48 + (y-6)^2
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y^2 -6y = 48 + y^2 -12y +36
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6y = 84
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y = 14
.
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x=y-6 = 14-6 = 8
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check in (2),,14 * 8 = 48 + 64 = 112,,,,ok
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Equations/201556: Evaluate the function.
Given that f(x) = (1)/(4-8x) , find f(r - 3).
A) (1)/(1-8r)
B) (1)/(28-8r)
C) (1)/(28+b)
D) (1)/(r-3-8x)
1 solutions
Answer 151875 by RAY100(1637) on 2009-06-30 16:42:48 (Show Source):
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Geometric_formulas/201599: This question is from textbook geometry
can you please help me slove ((( True of false Two right circular cones with radii 4 and 8, and heights 10 and 20, respectively, are similar. ))) 1 solutions
Answer 151871 by RAY100(1637) on 2009-06-30 16:11:21 (Show Source):
You can put this solution on YOUR website!In solid figures, if linear dims are proportional, figures are similar.
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Scale factor by radius are,,4/8 = 1/2,,,by height,,10/20 =1/2,,,,
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Therefore they are similar
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Exponents/201628: Dear tutor,I 've checked one of the problems which was like my question but I couldn't mach the answer with mine.could you help me in this way ?
Choose the answer Of if :
a.)
b.)
c.)
d.)
e.) 1 solutions
Answer 151849 by RAY100(1637) on 2009-06-30 14:33:32 (Show Source):
You can put this solution on YOUR website!x + 1/x =8
(x^2 +1 ) / x =8
x^2 +1 = 8x
x^2 -8x +1 =0
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using quadratic eqn,, x= 7.873,,.127
,
substitute either in
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X^4 +(1/x^4) = 3842
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checking answers, this matches (E) (8^4 -2^8 +2)
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Geometric_formulas/201600: This question is from textbook geometry
can you please help me solve (((Find the center of the circle with equation
(x-3)^2+(y+4)^2=25.))) 1 solutions
Answer 151848 by RAY100(1637) on 2009-06-30 14:10:45 (Show Source):
You can put this solution on YOUR website!(x-3)^2 +(y+4)^2 =25
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Remember form is,,,,(x-h)^2 +(y-k)^2 = r^2,,,(h,k) is center
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in our case, h=3,,,k=-4,,,r=5,,,or center is (3,-4)
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Exponential-and-logarithmic-functions/201601: Determine where the graph of the function is concave up and concave down (if you need to enter use infinity or - infinity)
f(x)=x^3-15x^2+12x+6
concave up
concave down
can someone help please
thanks
1 solutions
Answer 151847 by RAY100(1637) on 2009-06-30 14:05:32 (Show Source):
You can put this solution on YOUR website!y= x^3 -15x^2 +12x +6
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y' = 3x^2 -30x +12
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to find vertex, set slope(y') =0
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3x^2 -30x +12 =0
3(x^2 -10x +4) =0
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solve using quadratic eqn,,,x= 9.58,,,.417
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to find y,,,substitute in original eqn,,,,(9.58,-376.5),,,(.417,,8.47)
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since this is a positive cubic,,rises to right,,
1st vertex,,,(.417,8.47) is concave down,,,and
second vertex (9.58, -376.5) is concave up
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checking,,,(.5,8.375) (.3,8.277),,,ok cc down
(9.5,-376.4),(9.7, -376.3) ,,,,ok cc up
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Probability-and-statistics/201603: Card Figure: 1 A , 2 B's, & 3 C's. Die 1/6
Referring to the figure in, think about first picking a card and
then rolling the die. Give the probability in simplest form.
P(C number greater than 4)= 1 solutions
Answer 151842 by RAY100(1637) on 2009-06-30 13:33:22 (Show Source):
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Probability-and-statistics/201604: Card Figure: 1 A , 2 B's, & 3 C's. Die 1/6
Referring to the figure, think about first picking a card and
then rolling the die. Give the probability in simplest form.
P(B,number less than 5) 1 solutions
Answer 151839 by RAY100(1637) on 2009-06-30 13:30:12 (Show Source):
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Probability-and-statistics/201605: Card Figure: 1 A , 2 B's, & 3 C's. Die 1/6
Referring to the figure, think about first picking a card and
then rolling the die. Give the probability in simplest form.
P(A,not 2)= 1 solutions
Answer 151836 by RAY100(1637) on 2009-06-30 13:27:31 (Show Source):
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Sequences-and-series/201608: find the 6th term of the sequence which has a first term of 5 and has a common ratio of 4.2 1 solutions
Answer 151834 by RAY100(1637) on 2009-06-30 13:23:55 (Show Source):
You can put this solution on YOUR website!Geometric series has form,,,,a(n) = a(1) * r^(n-1)
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a(1) =5,,,,r=4.2,,,,,n= 6
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a(6) = 5*4.2^ 5 = 6534.56
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checking,,5,,21,,,88.2,,370.44,,1555.848,,6534.56,,,,,ok
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Sequences-and-series/201610: which is the 9th term of the sequence which has a first term of 1 and has a common ratio of 1.5 1 solutions
Answer 151832 by RAY100(1637) on 2009-06-30 13:16:33 (Show Source):
You can put this solution on YOUR website!Geometric sequence has form,,,,a(n) = a(1) r^(n-1)
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given,,,a(1) =1,,,r=1.5
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a(n) = 1* 1.5^(n-1)
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for n=9,,,,,a(9) = 1*1.5^8 = 25.629
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checking,, 1,,1.5,,2.25,,,3.375,,5.0625,,7.59375,,11.390,,17.086,,25.629,,,,,ok
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Polynomials-and-rational-expressions/201613: What is the largest four-digit number such that the second digit is one-fourth of the third digit, the third digit is twice the first digit, and the last digit is the same as the first digit?
Thank you!
1 solutions
Answer 151829 by RAY100(1637) on 2009-06-30 13:09:47 (Show Source):
You can put this solution on YOUR website!Let,,w,x,y,z,,,be four digits in order.
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x=1/4 y
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y=2w,,,,therefore x = 1/4 * 2w = w/2
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z=w
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rewriting the digits,,,,,w,,w/2,,,2w,,,w
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2w is "largest" digit,,,,like to set to 9 but also have a digit, (w/2) ,,,therefore 2w =8 is largest possible.
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restating digits,,,4,,,2,,,8,,,4,
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checking, numbers match criteria.
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