Question

The area of a rectangle is x²-4x-21
Write down an expression for the width and the length of
the rectangle.​

Answer 1

Answer:

Step-by-step explanation:

Area of rectangle= Length x Width

and the given Area is a quadratic expression

A=$x^{2} -4x-21$

We use the factorization method so,

we need 2 numbers that when multiplied we get -21 and when we add/subtract we get -4 so,

A=$x^{2} -7x+3x-21$

now we simplify,

A=$x(x-7)+3(x-7)$

A=$(x-7)(x+3)$

This looks familiar doesn't it, when we write the formula for the area of rectangle its

A= Length x Width and the equation here shows that

A= $(x-7)(x+3)$

So the expression for the length is x-7 and

the expression for the width is x+3 i think u have missed maybe some information on the question as such that the perimeter might be missing because length could be either x-7 or even x+3 same goes for width maybe someone can correct me if im wrong