Question

√217 - x = x-7 Solve this question for x. ASAP. x is also under root bracket

Answer 1

$\sqrt{217 - x} = x - 7 \\ take \: square \: both \: sides \\ 217 - x = ( {x - 7)}^{2} \\ 217 - x = {x}^{2} - 14x + 49 \\ {x}^{2} - 14x + x + 49 - 217 = 0 \\ {x}^{2} - 13x - 168 = 0 \\ {x}^{2} - 21x + 8x - 168 = 0 \\ x(x - 21) + 8(x - 21) = 0 \\ (x - 21)(x + 8) = 0 \\ x - 21 = 0 \\ x = 21 \\ x + 8 = 0 \\ x = - 8$