Question

The rectangle shown below has an area of 4(x+3) square units.

Answer 1

Remark

The area = 4*(x + 3) to start with. If you remove the brackets,

A = 4(x + 3)

A = 4*x + 3*4

A = 4x + 12 <<<<<< Answer for A

Part B

The area will become 4 times larger.

A = 4*(4x + 12)

A = 16x + 48

Argument

You may not be wholly satisfied with an unproved statement. I could prove it with algebra but it might be easier just to give an example.

Area = L * W

L = 10

W = 5

Area = 10*5

Area = 50

Now double both L and W

L = 20

W = 10

Area = L*W

Area = 20*10

Area = 200 which is 4 times the size of 50.