Question

The width of a rectangle is 7x units and its length is (3x - 8) units. what is the area of the rectangle if the length is doubled?

Answer 1

Answer:

Step-by-step explanation

Givens

Given Length: 3x - 8

Width: 7x

Area: 7x * (3x - 8)                  Remove the brackets

Area: 21x^2 - 56x

Now double the length

New Length = 2 * old length

old length = 3x - 8

New Length = 2(3x - 8)         Remove the brackets

New Length = 6x - 16

The width remains as 7x

Area = New Length * width

Area = (6x - 16)*7x                  Remove the brackets

Area = 42x^2 - 112x

Observe

42x^2 is twice as big as 21x^2

-112x is twice as small as 56x

So the area has changed by a factor 2