SOLUTION: I don't understand how to solve this problem. X^2-6x=16. So far I have X^2-6x+(6/2)^2=16 X^2-6x+36/4=16 I am unclear what to do after that so if you can help me, please.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: I don't understand how to solve this problem. X^2-6x=16. So far I have X^2-6x+(6/2)^2=16 X^2-6x+36/4=16 I am unclear what to do after that so if you can help me, please.      Log On


   

Question 154615: I don't understand how to solve this problem. X^2-6x=16. So far I have
X^2-6x+(6/2)^2=16
X^2-6x+36/4=16
I am unclear what to do after that so if you can help me, please.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2-6x=16 Start with the given equation.


x%5E2-6x-16=0 Subtract 16 from both sides.


Notice we have a quadratic equation in the form of ax%5E2%2Bbx%2Bc where a=1, b=-6, and c=-16


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-%28-6%29+%2B-+sqrt%28+%28-6%29%5E2-4%281%29%28-16%29+%29%29%2F%282%281%29%29 Plug in a=1, b=-6, and c=-16


x+=+%286+%2B-+sqrt%28+%28-6%29%5E2-4%281%29%28-16%29+%29%29%2F%282%281%29%29 Negate -6 to get 6.


x+=+%286+%2B-+sqrt%28+36-4%281%29%28-16%29+%29%29%2F%282%281%29%29 Square -6 to get 36.


x+=+%286+%2B-+sqrt%28+36--64+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-16%29 to get -64


x+=+%286+%2B-+sqrt%28+36%2B64+%29%29%2F%282%281%29%29 Rewrite sqrt%2836--64%29 as sqrt%2836%2B64%29


x+=+%286+%2B-+sqrt%28+100+%29%29%2F%282%281%29%29 Add 36 to 64 to get 100


x+=+%286+%2B-+sqrt%28+100+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%286+%2B-+10%29%2F%282%29 Take the square root of 100 to get 10.


x+=+%286+%2B+10%29%2F%282%29 or x+=+%286+-+10%29%2F%282%29 Break up the expression.


x+=+%2816%29%2F%282%29 or x+=++%28-4%29%2F%282%29 Combine like terms.


x+=+8 or x+=+-2 Simplify.


So the answers are x+=+8 or x+=+-2