Solving Equation 5

Revision as of 04:14, 11 November 2010 by Admin (Talk | contribs)

Solve : √(9x + 81) = x + 5

Solution: √(9x + 81) = x + 5

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

=> 9x + 81 = x² + 10x + 25

=> x² + x - 56 = 0

=> x² +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}.