Question

Please help 7th Grade Math​

Answer 1

Answer:

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

$A=16x^2-8x$

Hence, the 2nd option is correct.

Step-by-step explanation:

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

i.e.

$A=l\times w$

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:

$A=l\times w$

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

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

   $=\left(x+5+3x+4x-9\right)\times \:2x$

   $=2x\left(8x-4\right)$

    $=16x^2-8x$

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

$A=16x^2-8x$

Hence, the 2nd option is correct.