Question

A window in the shape of a rectangle as shown below has a width of x+5 and a length of x^2- 3x+7 express the area of the rectangle as a single polynomial in simplest form

Answer 1

Answer:

$x^3+x^2-5x+28$

Step-by-step explanation:

since a=lw, the area is (x^2-3x+7)(x+4)

1. distribute parentheses $\left(x^2-3x+7\right)\left(x+4\right)=x^2x+x^2\cdot \:4+\left(-3x\right)x+\left(-3x\right)\cdot \:4+7x+7\cdot \:4$

2. apply +(-a)=-a rule $x^2x+4x^2-3xx-3\cdot \:4x+7x+7\cdot \:4$

3. Simplify

    Steps to simplify:

$x^2x=x^3$

$3xx=3x^2$

$3\cdot \:4x=12x$

$7\cdot \:4=28$

$x^3+4x^2-3x^2-12x+7x+28$

4. Add like terms $=x^3+4x^2-3x^2-5x+28$

5. Add like terms $=x^3+x^2-5x+28$