Question 162831
You did not need to expand it.  This, is enough:
(2x-5)(x+8)=0 
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Notice that if EITHER then contents of the left parenthesis or the right parenthesis, is zero, then the ENTIRE left side is zero.
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Therefore, the solutions are found by setting the two term on the left to zero.
Solution 1:
(2x-5)=0
2x = 5
x = 5/2
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Solution 2:
(x+8)=0
x = -8
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Therefore,
x = {-8, 5/2}