SOLUTION: 15x^2+26x+8=0

Algebra ->  Test -> SOLUTION: 15x^2+26x+8=0      Log On


   

Question 575161: 15x^2+26x+8=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

15x%5E2%2B26x%2B8=0 Start with the given equation.


Notice that the quadratic 15x%5E2%2B26x%2B8 is in the form of Ax%5E2%2BBx%2BC where A=15, B=26, and C=8


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


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


x+=+%28-%2826%29+%2B-+sqrt%28+%2826%29%5E2-4%2815%29%288%29+%29%29%2F%282%2815%29%29 Plug in A=15, B=26, and C=8


x+=+%28-26+%2B-+sqrt%28+676-4%2815%29%288%29+%29%29%2F%282%2815%29%29 Square 26 to get 676.


x+=+%28-26+%2B-+sqrt%28+676-480+%29%29%2F%282%2815%29%29 Multiply 4%2815%29%288%29 to get 480


x+=+%28-26+%2B-+sqrt%28+196+%29%29%2F%282%2815%29%29 Subtract 480 from 676 to get 196


x+=+%28-26+%2B-+sqrt%28+196+%29%29%2F%2830%29 Multiply 2 and 15 to get 30.


x+=+%28-26+%2B-+14%29%2F%2830%29 Take the square root of 196 to get 14.


x+=+%28-26+%2B+14%29%2F%2830%29 or x+=+%28-26+-+14%29%2F%2830%29 Break up the expression.


x+=+%28-12%29%2F%2830%29 or x+=++%28-40%29%2F%2830%29 Combine like terms.


x+=+-2%2F5 or x+=+-4%2F3 Simplify.


So the solutions are x+=+-2%2F5 or x+=+-4%2F3