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

Step-by-step explanation:

Area of rectangle= Length x Width

and the given Area is a quadratic expression

A=

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=

now we simplify,

A=

A=

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=

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