Question

The function f(x) =4x+3 represents the length of a rectangle. The function g(x)=2x-5 represents the width of the rectangle.Use (f•g)(4) to determine the area of a rectangle

Answer 1

Answer: 32x-68

Step-by-step explanation:

(f•g) is equal to f(gx)

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

Which is 8x-20+3=8x-17

Now multiply by 4.

4(8x-17)

= 32x-68

Answer 2

Answer: 57 square units.

Step-by-step explanation:

Given : The  function $f(x) =4x+3$  represents the length of a rectangle.

The function $g(x)=2x-5$ represents the width of the rectangle.

Then , the area of the rectangle is given by :_

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

At x= 4,

$A=(f\cdot g)(4)=(4(4)+3)(2(4)-5)\\\\=(16+3)(8-5)=19\times3=57$

Hence, the area of a rectangle = 57 square units.