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| Math Central | Quandaries & Queries |
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Question from Kieran, a student: How could I work this out please f(x)= 3xsquared - 4x + 2 if f(2x) |
Kieran,
Let me try a similar example.
g(x) = 4x2 - 3x + 7, find g(3x).
What you need to do to find g(3x) is to take the expression for g(x), replace x by 3x and simplify. I get
g(3x) = 4(3x)2 - 3(3x) + 7.
Since (3x)2 = (3x)(3x)= 9x2 this simplifies to
g(3x) = 4(9x2) - 9x + 7 = 36x2 - 9x + 7.
Now try your problem.
Penny
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