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Question 148079: I need help with these algebra questions
1. Find the inverse of the function f(x)=8x+16
2. Write y=x^5 in log form
3. Write log 7 49=2 in expotonential form (log base 7 of 49 equals 2)
4. use the change-of-base formula (log,r=log r/log a
b b
to solve for x: x=log3 90
5. Solve for x: 9/(4x)+1/3=5/(2x)
6. Sove the system of linear equations: 2x+3y=-5 and y=2x+9
I get really confuse on #4, because after looking at the formula I found in the book to say; a,b and r are positive numbers, with a=1 (with slash through middle of =) and b=1(also with slash through middle of equal sign) then the formula property log,r=log r/log a
b b
the b is under the r and a like when putting x^2 I hope that makes sense to you.
Thanks
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 1. Find the inverse of the function f(x)=8x+16
Interchange x and y to get:
x = 8y + 16
Solve for y
y = (-1/*)x - 2
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2. Write y=x^5 in log form
log(base x) y = 5
-------------------------
3. Write log 7 49=2 in exponential form
7^2 = 49
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4. use the change-of-base formula (log,r=log r/log a
b b to solve for x: x=log3 90
x = [log 90]/[log 3]
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5. Solve for x: 9/(4x)+1/3=5/(2x)
Multiply thru by 12x to get:
27 + 4x = 30
4x = 3
x = 3/4
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6. Solve the system of linear equations: 2x+3y=-5 and y=2x+9
Substitute to solve for "x":
2x + 3(2x+9) =9
8x + 27 = 9
8x = -28
x = -19/4
---
Substitute into y = 2x+9 to solve for "y":
y = 2(-19/4)+9
y = -39/4 + 36/4
y = -3/4
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Cheers,
Stan H.
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