Q:

Why might algebra tiles not be a good tool to use to factor x^2 + 18x + 80? Explain.

Accepted Solution

A:
Algebra tiles might not be a good tool to use to factor the polynomial x^2 + 18xΒ  + 80 because you would need too many tiles and a large space to place them.

The algebra tiles procedure consists on using tiles to represent each kind of term: x^2, x and unit

It is easy to factor an expression like x^2 + 3x + 2 because you can do it placing one positive x^2 tile in the upper left corner, two x tiles on the right side of the x^2 tile, one x tile below the x^2 tile, and two unit tiles in the bottom right corner, since the factored expression is (x + 1)(x + 2).

But the factored expression of x^2 + 18x + 80 is (x + 10)(x + 8): 10 + 8 = 18 and 10 * 8 = 80.

Those factors means that the rectangle to be formed would need you to place one positive x^2 in the upper left corner, 10 x tiles on the right side of the x^2 tile, 8x tiles below the x^2 tile, and 80 unit tiles to fill the rectangle. That is not practical.