SOLUTION: My book gives an example of an quadratic equation, but I do not understand how it has been worked. Here is the one that I have to turn in on my home work x2-2x-13=0,and here is the

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: My book gives an example of an quadratic equation, but I do not understand how it has been worked. Here is the one that I have to turn in on my home work x2-2x-13=0,and here is the      Log On


   

Question 180712: My book gives an example of an quadratic equation, but I do not understand how it has been worked. Here is the one that I have to turn in on my home work x2-2x-13=0,and here is the example from the book: My e-mail address is, glen.a.harris@windstream.net
x2+3x-10=0
x2+3x=10
4x2+12x=40
4x2+12x+9=40+9
4x2+12x+9=49
2x+3=+7
2x+3=7 2x+3=-7
2x=4 2x=-10
x=2 x=-5
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
I'm not sure of the method that you're using, but here's the way that I'd do it:




x%5E2%2B3x-10=0 Start with the given equation.


Notice we have a quadratic equation in the form of ax%5E2%2Bbx%2Bc where a=1, b=3, and c=-10


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%28-10%29+%29%29%2F%282%281%29%29 Plug in a=1, b=3, and c=-10


x+=+%28-3+%2B-+sqrt%28+9-4%281%29%28-10%29+%29%29%2F%282%281%29%29 Square 3 to get 9.


x+=+%28-3+%2B-+sqrt%28+9--40+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-10%29 to get -40


x+=+%28-3+%2B-+sqrt%28+9%2B40+%29%29%2F%282%281%29%29 Rewrite sqrt%289--40%29 as sqrt%289%2B40%29


x+=+%28-3+%2B-+sqrt%28+49+%29%29%2F%282%281%29%29 Add 9 to 40 to get 49


x+=+%28-3+%2B-+sqrt%28+49+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-3+%2B-+7%29%2F%282%29 Take the square root of 49 to get 7.


x+=+%28-3+%2B+7%29%2F%282%29 or x+=+%28-3+-+7%29%2F%282%29 Break up the expression.


x+=+%284%29%2F%282%29 or x+=++%28-10%29%2F%282%29 Combine like terms.


x+=+2 or x+=+-5 Simplify.


So the answers are x+=+2 or x+=+-5