# Solving Equation 5

### From Homeworkwiki

**Solve :** **√(9x + 81) = x + 5**

**Solution:** √(9x + 81) = x + 5

=> 9x + 81 = (x+5)^{2} [ Squaring both side ]

=> 9x + 81 = x^{2} + 10x + 25

=> x^{2} + x - 56 = 0

=> x^{2} +8x - 7x - 56 = 0

=> x( x + 8) - 7(x +8) = 0

=> (x-7)(x+8) = 0

so, either x-7 = 0

=> x=7

or, x+8 = 0

=> x=-8

So, x= {7,-8}.