what's the value of x

Question

The area of the rectangle is 140 square units the length of the rectangle is x+2 and the width of the rectangle is 4x what's the value of x

Answer 1

Area of rectangle is - width * length.

Given in problem - Area = 140

Solution: Area = width * length
140 = 4x * (x+2)

140 = 4x² + 8x

4x² + 8x -140 = 0
i.e.
x² + 2x - 35

Solve this quadratic equation for x.

you will get below values for x:
x = -7 or x =5
x can't be negative as it will make length and width negative, which is impossible.
So x=5.

Verify the answer.
length = x +2 = 5+2 = 7
width = 4*x = 4*5 = 20
area = 7 * 20 = 140

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