SOLUTION: I need help. I am taking my final exam this weekend and I am doing the practice exam. I need desperately to understand step by step how to do the following equation as I get every

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: I need help. I am taking my final exam this weekend and I am doing the practice exam. I need desperately to understand step by step how to do the following equation as I get every       Log On


   

Question 470144: I need help. I am taking my final exam this weekend and I am doing the practice exam. I need desperately to understand step by step how to do the following equation as I get every example wrong.
a^2+3a-28=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'm going to use the variable x instead of 'a'.


x%5E2%2B3x-28=0 Start with the given equation.


Notice that the quadratic x%5E2%2B3x-28 is in the form of Ax%5E2%2BBx%2BC where A=1, B=3, and C=-28


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-%283%29+%2B-+sqrt%28+%283%29%5E2-4%281%29%28-28%29+%29%29%2F%282%281%29%29 Plug in A=1, B=3, and C=-28


x+=+%28-3+%2B-+sqrt%28+9-4%281%29%28-28%29+%29%29%2F%282%281%29%29 Square 3 to get 9.


x+=+%28-3+%2B-+sqrt%28+9--112+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-28%29 to get -112


x+=+%28-3+%2B-+sqrt%28+9%2B112+%29%29%2F%282%281%29%29 Rewrite sqrt%289--112%29 as sqrt%289%2B112%29


x+=+%28-3+%2B-+sqrt%28+121+%29%29%2F%282%281%29%29 Add 9 to 112 to get 121


x+=+%28-3+%2B-+sqrt%28+121+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-3+%2B-+11%29%2F%282%29 Take the square root of 121 to get 11.


x+=+%28-3+%2B+11%29%2F%282%29 or x+=+%28-3+-+11%29%2F%282%29 Break up the expression.


x+=+%288%29%2F%282%29 or x+=++%28-14%29%2F%282%29 Combine like terms.


x+=+4 or x+=+-7 Reduce.


So the solutions are x+=+4 or x+=+-7