Question

Factor this trinomial.
x2 - 8x+15

Answer 1

(x-3)(x-5)

Explanation:

The expression is:

x2 - 8x+15

Break the middle term:

Coefficient of first term will be multiplied by constant

1*15 = 15

Now we have to find out which numbers will be multiplied to get 15

and also by adding those numbers we get the middle term:

3*5=15

3+5 = 8

Now break the middle term:

x^2-3x-5x+15

x(x-3)-5(x-3)

(x-5)(x-3)....

The factors are (x-5)(x-3)....

Answer 2

(x - 5)(x - 3)

Explanation:

You need two numbers that multiply to 15 and add to 8. There aren't many numbers that will do that.

15 and 1 is one pair of numbers. They multiply to 15 but don't add to 8.

6 and 2 add to 8 but don't multiply to 15.

5 and 3. This in some form is your answer, but handle it carefully.

(x - 5)(x - 3)

The 5 and 3 both have to be minus.