SOLUTION: Solve 80=-5t^2-20t+100

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Question 118355: Solve
80=-5t^2-20t+100
Answer by tutorcecilia(2152) About Me  (Show Source):
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80=-5t^2-20t+100
-5t%5E2-20t%2B100-80%29=0 [subtract 80 from both sides]
-5t%5E2-20t%2B20%29=0 [simplify]
.
x+=+%28-%28-20%29+%2B-+sqrt%28+%28-20%29%5E2-%284%2A-5%2A20+%29%29%29%2F%282%2Aa%29+
.
x+=+%2820%29+%2B-+sqrt%28+%28%28400%29-%28-400%29+%29%29%2F%28-10%29%29%29+
.
x+=+%2820%29+%2B-+sqrt%28%28+%28800%29+%29%29%2F%28-10%29%29%29+
.
x=0.828
and
x=-4.828