SOLUTION: Do I replace the (x) with 15? g(x) = -2x -3 Find x if g(x) = 15

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Question 1135377: Do I replace the (x) with 15?
g(x) = -2x -3
Find x if g(x) = 15
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
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Do I replace the (x) with 15?
g(x) = -2x -3
Find x if g(x) = 15
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Read the function definition and the question again. The meaning is clear.


Do you replace x with 15?
Why?

What if you did?
g%2815%29=-2%2A15-3=-30-3, but "Find x if g(x) = 15", means something else. Do you see?

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g%28x%29=15=-2x-3
-2x-3=15
-2x=18
x=18%2F%28-2%29
highlight%28x=-9%29

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

Do I replace the (x) with 15?
g(x) = -2x -3
Find x if g(x) = 15
No!! 

You're given that g(x) = 15, so what you should REPLACE with 15 is g(x), not x.