Question

Problem 2: The area of a

rectangular desk is given
by the trinomial x²-7x-18.
What are the dimensions
of the desk? (10 points)

Answer 1

Answer: (x-9) and (x+2)

Explanation:

You would first have to break the trinomial down into 2 factors.

Since there are two minuses in the trinomial, start off like this : (x- __) (x+__)

Now, what two numbers add to -7, and multiply to -18?

9 and 2, with one term being negative.

Since the 2nd term in the trinomial is a negative, there must be a number added that has a greater negative term than the other positive term, therefore, making 9 the negative term, since 2-9 is -7.

And -9 times 2 is -18.

Now fill in the blanks : (x-9)(x+2)

Since (x-9) and (x+2) are multiplied by each other, they are the dimensions of the desk, being L x W.

Now let's double check the factors:

(x-9)(x+2)

Distribute the terms.

x^2 +2x -9x -18

x^2-7x-18

There, hoped that helped :D