Question 173410This question is from textbook Introductory Algebra
: Solve the equation
x(x-3) = 40
This question is from textbook Introductory Algebra
Answer by KnightOwlTutor(293)   (Show Source):
You can put this solution on YOUR website! x(x-3) = 40
Expand the equation
x^2-3X=40
subtract 40 from both sides
x^2-3X-40=0
Find possible factors for 40
(40,1) (2,20) (8,5)
We see that the 40 has a negative sign which means that one of the factors is negative.
Then we find which two factors when added together can give you -3
I can see from the list that the only possible answer is 5,8
(x-8)(x+5)=0 is the factored form of the above equation
Therefore the answers are x=8 and x=-5
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