SOLUTION: Solve using the quadratic formula: x squared= 8x-16 I am really confused, because this doesn't really follow the formula. Thanks in advance!! :)

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Solve using the quadratic formula: x squared= 8x-16 I am really confused, because this doesn't really follow the formula. Thanks in advance!! :)      Log On


   

Question 196637This question is from textbook Prentice Hall Algebra 1
: Solve using the quadratic formula:
x squared= 8x-16
I am really confused, because this doesn't really follow the formula.
Thanks in advance!! :) This question is from textbook Prentice Hall Algebra 1

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2=+8x-16+ Start with the given equation.


x%5E2-8x=-16+ Subtract 8x from both sides.


x%5E2-8x%2B16=0+ Add 16 to both sides.


Notice we have a quadratic in the form of Ax%5E2%2BBx%2BC where A=1, B=-8, 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-%28-8%29+%2B-+sqrt%28+%28-8%29%5E2-4%281%29%2816%29+%29%29%2F%282%281%29%29 Plug in A=1, B=-8, and C=16


x+=+%288+%2B-+sqrt%28+%28-8%29%5E2-4%281%29%2816%29+%29%29%2F%282%281%29%29 Negate -8 to get 8.


x+=+%288+%2B-+sqrt%28+64-4%281%29%2816%29+%29%29%2F%282%281%29%29 Square -8 to get 64.


x+=+%288+%2B-+sqrt%28+64-64+%29%29%2F%282%281%29%29 Multiply 4%281%29%2816%29 to get 64


x+=+%288+%2B-+sqrt%28+0+%29%29%2F%282%281%29%29 Subtract 64 from 64 to get 0


x+=+%288+%2B-+sqrt%28+0+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%288+%2B-+0%29%2F%282%29 Take the square root of 0 to get 0.


x+=+%288+%2B+0%29%2F%282%29 or x+=+%288+-+0%29%2F%282%29 Break up the expression.


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


x+=+4 or x+=+4 Simplify.


So the answer is x+=+4 (with a multiplicity of 2)