How do you solve x+72=x?

1 Answer
Mar 2, 2018

Change the equation into a quadratic equation and use the formula to solve for x. (x=9)

Explanation:

Start off by squaring everything.

x+72=x

x+72=x2

Now you can bring everything to one side of the equation.
x2x72=0

Looking at the above equation, we can use the quadratic formula to find the value of x.
b±(b24ac)2a

Note: the values are the following:
(ax2+bx+c)a=1,b=1,c=72

1±(124(1)(72))2(1)
1±2892

x=9x=8

9+72=9

9=9

8+72=8

8=8

-8 Doesn't work, so x must equal 9.