Question

Dada a função f: R R, definida por f(x-1)=3x+4,então o valor de f(x) é:

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Answer 1

$f(x)=ax+b\\f(x-1)=a(x-1)+b\\f(x-1)=ax-a+b\\3x-4=ax-a+b$

$\mathsf{\begin{cases}ax=3x\\-a+b=4\end{cases}}$

$ax=3x\\a=\dfrac{3x}{x}=3$

$-a+b=4\\-3+b=4\\b=4+3\\b=7$

$\boxed{\boxed{\mathsf{f(x)=3x+7}}}$