Question

If function F is defined by f(x) = 3x^2 + 5, what is f(x-4)

Answer 1

Answer:

The function f(x) when x=x-4 is $f(x-4)=3x^2-24x+53$  or $f(x-4)=3x(x-8)+53$

Step-by-step explanation:

Given function f is defined by $f(x)=3x^2+5$

Now to find the function f(x-4):

$f(x)=3x^2+5$

Put x=x-4 in the above function we get

$f(x-4)=3(x-4)^2+5$

$f(x-4)=3(x^2-2(x)(4)+4^2)+5$ (using the formula $(a-b)^2=a^2-2ab+b^2$)

$f(x-4)=3(x^2-8x+16)+5$

$f(x-4)=3x^2-24x+48+5$ (adding the like terms)

$f(x-4)=3x^2-24x+53$

$f(x-4)=3x(x-8)+53$

Therefore $f(x-4)=3x^2-24x+53$  or $f(x-4)=3x(x-8)+53$

The function f(x) when x=x-4 is $f(x-4)=3x^2-24x+53$  or $f(x-4)=3x(x-8)+53$