SOLUTION: Please help me solve this, I need to solution for r: 4r^2-13r+10=0

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Question 241430: Please help me solve this, I need to solution for r: 4r^2-13r+10=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

4r%5E2-13r%2B10=0 Start with the given equation.


Notice that the quadratic 4r%5E2-13r%2B10 is in the form of Ar%5E2%2BBr%2BC where A=4, B=-13, and C=10


Let's use the quadratic formula to solve for "r":


r+=+%28-B+%2B-+sqrt%28+B%5E2-4AC+%29%29%2F%282A%29 Start with the quadratic formula


r+=+%28-%28-13%29+%2B-+sqrt%28+%28-13%29%5E2-4%284%29%2810%29+%29%29%2F%282%284%29%29 Plug in A=4, B=-13, and C=10


r+=+%2813+%2B-+sqrt%28+%28-13%29%5E2-4%284%29%2810%29+%29%29%2F%282%284%29%29 Negate -13 to get 13.


r+=+%2813+%2B-+sqrt%28+169-4%284%29%2810%29+%29%29%2F%282%284%29%29 Square -13 to get 169.


r+=+%2813+%2B-+sqrt%28+169-160+%29%29%2F%282%284%29%29 Multiply 4%284%29%2810%29 to get 160


r+=+%2813+%2B-+sqrt%28+9+%29%29%2F%282%284%29%29 Subtract 160 from 169 to get 9


r+=+%2813+%2B-+sqrt%28+9+%29%29%2F%288%29 Multiply 2 and 4 to get 8.


r+=+%2813+%2B-+3%29%2F%288%29 Take the square root of 9 to get 3.


r+=+%2813+%2B+3%29%2F%288%29 or r+=+%2813+-+3%29%2F%288%29 Break up the expression.


r+=+%2816%29%2F%288%29 or r+=++%2810%29%2F%288%29 Combine like terms.


r+=+2 or r+=+5%2F4 Simplify.


So the solutions are r+=+2 or r+=+5%2F4