Question

PLEASE HELP

Answer 1

Answer:

After solving we get (f.g)(5)=-115

But the correct option is not given in the question.

Step-by-step explanation:

We are given:

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

We need to find (f.g)(5)

First we will multiply f and g to find (f.g) i.e

$(f.g)(x)= f(x) \times g(x)\\(f.g)(x) = (4x + 3)(-2x + 5)\\(f.g)(x)=4x(-2x+5)+3(-2x+5)\\(f.g)(x)=-8x^2+20x-6x+15\\(f.g)(x)=-8x^2+14x+15$

Now putting x=5

$(f.g)(x)=-8x^2+14x+15\\Put \ x=5\\(f.g)(5)=-8(5)^2+14(5)+15\\(f.g)(5)=-8(25)+70+15\\(f.g)(5)=-200+70+15\\(f.g)(5)=-115$

So, after solving we get (f.g)(5)=-115

But the correct option is not given in the question.