Questions on Algebra: Evaluation of expressions, parentheses answered by real tutors!

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Question 188699: -7=-35
shouldn't this be a positive 5. two negatives should equal a positive if my memory serves me correctly.

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Question 188723: USE >, =, or < for ? to form a true sentence.
3 over 8 ? - 13over 16

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Question 188720: in 2001, there was an estimated 900 million cell phone users and 600 million PC users in the world. what is the ratio of PC users to cell phone user?
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Question 188719: claude's college tuition was 4200. a loan was obtained for 2/3 of the tuition. for how much was the loan?
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Question 188789: I started the problem, but not sure if i did it right and I'm not exactly sure what the question is asking me to do. I was given a formula and guessed how to get the answer. Any help is much appreciated!
Problem as stated on homework:
1.) A simple model for the mutual potential energy, V, of a pair of inert gas atoms is the Lennard-Jones function, V=E%5B%28%28a%29%2F%28r%29%5E12%29-+2%28%28a%29%2F%28r%29%5E6%29%29%5D, where r is the distance between the atonms and E and a are positive constants (E having units of energy, while a has units of distance).
a.) At what distance between the atoms is the potential enery a minimum?
I looked up some info on Wikipedia and found that V%28r%29=E+%28%28%28r+min%29%2F%28r%29%5E12%29-+2%28%28rmin%29%2F%28r%29%5E6%29%29
F.Y.I.in the numerators r is regular size and 'min' is subscript.
then where rmin=2%5E%281%2F6%29a is the distance at the minimum of the potential.
b.)What is the value of the potential energy?
If if i did the first part wrong, my answer will be wrong here. Also, i don't know how to get a number value from the equation above...
Thank you very much for any help! If anyone could please send this to me by the sometimes tonight. I have to turn it in by 3:15pm on monday.

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Question 188917: 10x^2-30x+20/x^2-1
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Question 189065: 82%2F3*21%2F4/31%2F2/21%2F3
I'm not sure how to go about solving this, I keep getting stuck. Please help thank you.

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Question 190269: How do you write this mathematical expression using parentheses and brackets.
"Subtract 6 from 16. Divide this difference by 5. Multiply this quotient by 8."

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Question 190397: write as a mathematical expression using parentheses and brackets. then evaluate: "substract 6 from 16. divide the difference by 5. multiply this quotient by 8"
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Question 190842: We are working on logarithms. This was added to our prefinal homework. I am so confused at this point.

Given F(x) = 3x-2, evaluate the following.
a. F(-4)
b. F(-1)
c. F(0)
Here is what i've done so far after several attempts I keep doing it different and confusing myself. I need to understand as finals are next week. Thank you for any help.
f(F,x)=3^(x-2),F(-4)
Evaluate F(-4) by replacing x with -4 in the function.
F(-4)=3^((-4)-2)
F(-4)=(1)/(729)

((1)/(729))

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Question 191041: Every time I work these I get lost. I'm working out review of a crash class (7weeks) to take a final Friday and my confidence of understanding these is still not good.
Given f(x) = e-2x + 1, evaluate the following. Round to the nearest ten-thousandth.
f(-1)
f(3)
f(-2)
Show your work here:
f(-1)=e -2(-1)+1=x-1
f(-1)=e^2+1
f(-1)=7.389+1
f(-1) = 8.389

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Question 191309: (7-2)/5
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Question 191650: please help me evaluate this problem

What is d(3a+c)

if a is -2..if b= -1 c= 2 abd d= one fourth

thanks

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Question 191660: please help me evaluate

d(ab-c)

when a = -2 b = -1 c=2 and d = 1 fourth

thanks

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Question 191673: please help me evaluate this problem.

(ac+b)^3

a= -2 b = -1 c=2 and d = 1 fourth

thank you

--Tommy

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Question 191697: factor expression completely
2n^2-3mn+m^2

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Question 192385: A pet store manager had 80 gold fish in stock, she brought G more gold fish which expression can be used to model the number of gold fish she has now?
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Question 192680: How do I solve 2t squared minus 6t minus 20 equal zero
How do I solve y=(2x + 3)(minus 5)?
how do I solve x squared + 2x=8
What is the factored form of 3x squared plus 11x-4

The Teacher did not hand out Math books. Therefore, I cannot provide you with an ISBN

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Question 192902: Evaluate the expression -12(2x-1)-x^2 if x = -3

A= 75 B= 38 C = -45 or D = -57

thank you

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Question 193313: I HAVE A PLACEMENT TEST AND THIS QUESTION IS TOUGH FOR ME HOW DO I ANSWER
2X^2+3XY-4Y^2 WHEN X=2 AND Y=-4 I HAVE TRIED MANY TIMES BUT I CANNOT FIGURE IT OUT!! PLEASE HELP ME SO I PASS THIS TEST!!

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Question 193322:
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Question 193375: x^2 + x-20/ x^2 -16 Find answer in lowest terms

answer x+5/x+4
need a full break down of how the answer came about because i got a different answer i got was x+5/4 what did i do wrong ?

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Question 193421: A=h(a+b)/2
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Question 193585: x^2 + x -20/x^2 -16

answer:x+5/x+4
why is the answer x+5/ x+4 anyone can give a full break down why

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Question 193587: 1/y + 1/y+2
divided by
1/y- 1/y+2

answer:y+1 i think my text book is wrong anyone know if this is the right answer and if it is can u give a full break down on why the answer is y+1

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Question 193581: 5^-1 + 2^-1-3^0.
ANSWER: -3/10
anyone knows why the answer is -3/10 please give a full break down

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Question 193722: T^2 - 2T=15

answer (-3,5)
need a full break down on why the answer is -3,5

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Question 193722: T^2 - 2T=15

answer (-3,5)
need a full break down on why the answer is -3,5

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Question 193726: z^2/ z-3 - z/z+3


answer: z3 + 2z^2 + 3z/ (z-3) (z+3)
anyone can give me a full break down on why the answer is z3 +2z^2 +3z

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Question 193726: z^2/ z-3 - z/z+3


answer: z3 + 2z^2 + 3z/ (z-3) (z+3)
anyone can give me a full break down on why the answer is z3 +2z^2 +3z

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Question 193737: express [-2,6] as a set using absolute value and an equality
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Question 193736: Express [-1,9] as a set using absolute value and an inequality
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Question 194332: z^2 - 11z + 24
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Question 194409: 4b
---
a
a= -8
b= 6

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Question 194902: (sqrt5 - sqrt7)^2

answer:12-2 sqrt 35

need a full break down of why the answer is 12-2 sqrt 35 i know that the foil method must be applied

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Question 194998: 6x+4
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Question 195002: Simplify the expression by first factorising the numerator and the denominator
7x+14y
_____________
3x+6y+nx+2ny

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Question 194996: (5x-18)+(4x+7)
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Question 194995: (3x-14)+(2x+9)
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Question 195559: 3sqrty4^/^6sqrty^5 the only thing is the 3 and the 6 are the little numbers in on top of the leg of the square root sign the 4 and 5 is above the letter y's
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Question 195788: i want to know when you have a problem like (3xz^3)2 divided by x^4z^6 do you multiply the outside exponent (2) or is it added to the inside exponet is it
2 x 3 or 2 + 3 ?

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Question 196280: -[4x+3(4x+2)-2(x-4)]

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Question 196970: A food store makes a 9-lb mixture of peanuts, cashews, and raisins. Peanuts cost $1.50 per pound, cashews cost $2.00 per pound, and raisins cost $1.00 per pound. The mixture calls for twice as much peanuts than cashews. The total cost of the mixture is $13.00. How much of each ingredient did the store use?
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Question 197141: a strawbroom is made up a broom handle and broom shafts attached to the end of the broom. if the total length of the straw broom is broom is 63 inches. write and expression for the length of the handle if the broomcorn shafts are x inches long.
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Question 197163: a retailer wants a 70% markup on the selling price of an item that costs him $50. write the equation for the selling price in words. write the equation using x selling price.
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Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585, 586..630, 631..675, 676..720, 721..765, 766..810, 811..855, 856..900, 901..945, 946..990, 991..1035, 1036..1080, 1081..1125, 1126..1170, 1171..1215, 1216..1260, 1261..1305, 1306..1350, 1351..1395, 1396..1440, 1441..1485, 1486..1530, 1531..1575, 1576..1620, 1621..1665, 1666..1710, 1711..1755, 1756..1800, 1801..1845, 1846..1890, 1891..1935, 1936..1980, 1981..2025, 2026..2070, 2071..2115, 2116..2160, 2161..2205, 2206..2250, 2251..2295, 2296..2340, 2341..2385, 2386..2430, 2431..2475, 2476..2520, 2521..2565, 2566..2610, 2611..2655, 2656..2700, 2701..2745, 2746..2790, 2791..2835, 2836..2880, 2881..2925, 2926..2970, 2971..3015, 3016..3060, 3061..3105, 3106..3150, 3151..3195, 3196..3240, 3241..3285, 3286..3330, 3331..3375, 3376..3420, 3421..3465, 3466..3510, 3511..3555, 3556..3600, 3601..3645, 3646..3690, 3691..3735, 3736..3780, 3781..3825, 3826..3870, 3871..3915, 3916..3960, 3961..4005, 4006..4050, 4051..4095, 4096..4140, 4141..4185, 4186..4230, 4231..4275, 4276..4320, 4321..4365, 4366..4410, 4411..4455, 4456..4500, 4501..4545, 4546..4590, 4591..4635, 4636..4680, 4681..4725, 4726..4770, 4771..4815, 4816..4860, 4861..4905, 4906..4950, 4951..4995, 4996..5040, 5041..5085, 5086..5130, 5131..5175, 5176..5220, 5221..5265, 5266..5310, 5311..5355, 5356..5400, 5401..5445, 5446..5490, 5491..5535, 5536..5580, 5581..5625, 5626..5670, 5671..5715, 5716..5760, 5761..5805, 5806..5850, 5851..5895, 5896..5940, 5941..5985, 5986..6030, 6031..6075, 6076..6120, 6121..6165, 6166..6210, 6211..6255, 6256..6300, 6301..6345, 6346..6390, 6391..6435, 6436..6480, 6481..6525, 6526..6570, 6571..6615, 6616..6660, 6661..6705, 6706..6750, 6751..6795, 6796..6840