SOLUTION: 8c^2+21c+10=0

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Question 195548: 8c^2+21c+10=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
8c%5E2%2B21c%2B10=0 Start with the given equation.


Notice we have a quadratic equation in the form of ac%5E2%2Bbc%2Bc where a=8, b=21, and c=10


Let's use the quadratic formula to solve for c


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


c+=+%28-%2821%29+%2B-+sqrt%28+%2821%29%5E2-4%288%29%2810%29+%29%29%2F%282%288%29%29 Plug in a=8, b=21, and c=10


c+=+%28-21+%2B-+sqrt%28+441-4%288%29%2810%29+%29%29%2F%282%288%29%29 Square 21 to get 441.


c+=+%28-21+%2B-+sqrt%28+441-320+%29%29%2F%282%288%29%29 Multiply 4%288%29%2810%29 to get 320


c+=+%28-21+%2B-+sqrt%28+121+%29%29%2F%282%288%29%29 Subtract 320 from 441 to get 121


c+=+%28-21+%2B-+sqrt%28+121+%29%29%2F%2816%29 Multiply 2 and 8 to get 16.


c+=+%28-21+%2B-+11%29%2F%2816%29 Take the square root of 121 to get 11.


c+=+%28-21+%2B+11%29%2F%2816%29 or c+=+%28-21+-+11%29%2F%2816%29 Break up the expression.


c+=+%28-10%29%2F%2816%29 or c+=++%28-32%29%2F%2816%29 Combine like terms.


c+=+-5%2F8 or c+=+-2 Simplify.


So the answers are c+=+-5%2F8 or c+=+-2