How do you solve using the completing the square method # x^2+8x-9=0#?
1 Answer
Mar 18, 2016
Completing the square is designed to give you a perfect square trinomial on the left of an equation.
Explanation:
-
Get any constants on the right side.
#x^2+8x=9# -
Add
#(b/2)^2=(8/2)^2# to both sides
#x^2+8x+16=9+16# -
Factor the left.
#(x+4)^2=25# -
Square root both sides.
#(x+4)=+-5# -
#x={5-4,-5-4} = {1,-9}#
