Question

Please help 7th Grade Math​

Answer 1

The expression of the area of rectangle ABCD as simplified polynomial will be:

`A=16x^2-8x`

Hence, the 2nd option is correct.

Explanation:

As we know that the area of a rectangle can be obtained by multiplying the length by the width.

i.e.

`A=l* w`

Given

The length of a rectangle ABCD =
`l` =
`(x+5) + (3x) + (4x-9)`

The width of a rectangle =
`w` =
`2x`

so the expression of the area of rectangle ABCD as simplified polynomial will be:

`A=l* w`

`A=\left[\left(x+5\right)\:+\:\left(3x\right)\:+\:\left(4x-9\right)\right]\:* \left[2x\right]`

`=\left(\left(x+5\right)+\left(3x\right)+\left(4x-9\right)\right)\left(2x\right)`

`=\left(x+5+3x+4x-9\right)* \:2x`

`=2x\left(8x-4\right)`

`=16x^2-8x`

Therefore, the expression of the area of rectangle ABCD as simplified polynomial will be:

`A=16x^2-8x`

Hence, the 2nd option is correct.