Question 150829: Hi, please answer this question.
I have: x^2-x-5=0. I know how to solve this using the quadratic equation method. The answers I get are (1+-sqrt(21))/2.
But instead of using the quadratic formula, can't I just say:
x^2-x=5
x(x-1)=5
x=5 or x=6
How come this answer is different from the one using the quadratic formula???
Thank you.: Hi, please answer this question.
I have: x^2-x-5=0. I know how to solve this using the quadratic equation method. The answers I get are (1+-sqrt(21))/2.
But instead of using the quadratic formula, can't I just say:
x^2-x=5
x(x-1)=5
x=5 or x=6
How come this answer is different from the one using the quadratic formula???
Thank you.
Answer by jim_thompson5910(8006)  (Show Source):
You can put this solution on YOUR website!You're thinking of the zero product property. The zero product property says that if  , then  or 
However, if you have  where in this case  , you cannot say that  or 
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