SOLUTION: how do you use the quadratic formula to solve 5y^2+5y=9? please round to the nearest hundreth

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Question 171872: how do you use the quadratic formula to solve 5y^2+5y=9? please round to the nearest hundreth
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

5y%5E2%2B5y=9 Start with the given equation.


5y%5E2%2B5y-9=0 Subtract 9 from both sides.


Notice we have a quadratic equation in the form of ay%5E2%2Bby%2Bc where a=5, b=5, and c=-9


Let's use the quadratic formula to solve for y


y+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29 Start with the quadratic formula


y+=+%28-%285%29+%2B-+sqrt%28+%285%29%5E2-4%285%29%28-9%29+%29%29%2F%282%285%29%29 Plug in a=5, b=5, and c=-9


y+=+%28-5+%2B-+sqrt%28+25-4%285%29%28-9%29+%29%29%2F%282%285%29%29 Square 5 to get 25.


y+=+%28-5+%2B-+sqrt%28+25--180+%29%29%2F%282%285%29%29 Multiply 4%285%29%28-9%29 to get -180


y+=+%28-5+%2B-+sqrt%28+25%2B180+%29%29%2F%282%285%29%29 Rewrite sqrt%2825--180%29 as sqrt%2825%2B180%29


y+=+%28-5+%2B-+sqrt%28+205+%29%29%2F%282%285%29%29 Add 25 to 180 to get 205


y+=+%28-5+%2B-+sqrt%28+205+%29%29%2F%2810%29 Multiply 2 and 5 to get 10.


y+=+%28-5%2Bsqrt%28205%29%29%2F%2810%29 or y+=+%28-5-sqrt%28205%29%29%2F%2810%29 Break up the expression.


So the answers are y+=+%28-5%2Bsqrt%28205%29%29%2F%2810%29 or y+=+%28-5-sqrt%28205%29%29%2F%2810%29


which approximate to y=0.932 or y=-1.932


So to the nearest hundredth, the answers are y=0.9 or y=-1.9