SOLUTION: Find the possible values of r in this equation r^2 -7r -8=0

Question 271999: Find the possible values of r in this equation
r^2 -7r -8=0
Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!

This is a quadratic equation (because of the term). So we want a zero on one side (which we already have) and then we either factor the other side or use the Quadratic Formula. I prefer factoring when possible and this equation factors fairly easily. As a trinomial with a 1 in front of the squared term, this can be factored by answering the question: "What factors of the number at the end (-8) that add up to the coefficient in the middle (-7)?" With a little thought and perhaps some trial and error, we should find that the only pair of factors of -8 that add up to -7 are: -8 and 1. So the equation factors into:

From the Zero Product Property we know that this product can only be zero if one of the factors is zero. So:
or
Solving these we get:
or
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