Question

Complete the square? x^2-7x-6=0

Answer 1

x^2-7x-6=0

x^2-7x-6+6=0+6

x^2-7x=6

x^2-7x+49/4=6+49/4 ... *** See note below ***

(x-7/2)^2 = 73/4

(x-7/2)^2 - 73/4 = 0


Note: on the line marked with 3 stars *** you take half of the x coefficient -7 to get -7/2 and you square it to get 49/4. Then you add this to both sides.

Answer 2

How would I solve this using the Quadrtic formula?

Answer 3

Start with


\[\Large x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}\]


and plug in a = 1, b = -7, c = -6 to get


\[\Large x = \frac{-(-7)\pm\sqrt{(-7)^2-4(1)(-6)}}{2(1)}\]


then evaluate


\[\Large x = \frac{7\pm\sqrt{49-(-24)}}{2}\]


\[\Large x = \frac{7\pm\sqrt{49+24}}{2}\]


I'll let you finish.