Question

Which of the following represents the area of a rectangle whose length is 5x − 3 and whose width is x + 7?

Answer 1

Answer : option C, 5x2 + 32x − 21

In the rectangle, the length = 5x - 3 and width = x + 7

We know the formula for area of rectangle = length * width

Area of rectangle = (5x-3)(x+7)

WE multiply it using FOIL method

F - First terms, 5x * x = $5x^2$

O- Outer terms, 5x * 7 = 35x

I - Inner terms, -3 * x= -3x

L - Last terms, -3 * 7 = -21

Now we add all the terms

$5x^2 +35x -3x -21$

combine like terms

$5x^2 +32x -21$

So area of a rectangle = $5x^2 +32x -21$