SOLUTION: Hi, my math book does not explain the "step by step" procedure so I don't know how to do each step. Would you please explain how you came up with each answer? thank you. x^2+x

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Hi, my math book does not explain the "step by step" procedure so I don't know how to do each step. Would you please explain how you came up with each answer? thank you. x^2+x      Log On


   

Question 406025: Hi, my math book does not explain the "step by step" procedure so I don't know how to do each step. Would you please explain how you came up with each answer?
thank you.
x^2+x-20=0
x=-b+-sqrt b(^2-4ac)/(2a)
x= x sqrt (x^2-4(1)(20))/(2(1))
x= sqrt (x^2-80)/ (2(1)) Now i am stuck, how to sqrt or factor it



Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2Bx-20=0
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ till here you were absolutely right
Look at formula of the quadratic equation ax%5E2%2Bbx%2Bc=0, a, b are coefficients before x%5E2 and x, c is the free term
so a=1, b=1, c=-20, put in formula
x+=+%28-1+%2B-+sqrt%28+1%5E2-4%2A1%2A%28-20%29+%29%29%2F%282%2A1%29+
x+=+%28-1+%2B-+sqrt%28+81+%29%29%2F2+
x1+=+%28-1+%2B9%29%2F2+ or x2+=+%28-1+-9%29%2F2+
x1+=+4+ or x2+=+-5