Question

solve x2+4x-21=0 find the value of x
$x { }^{2} + 4x - 21 = 0$
find the value of X

Answer 1

OK... Here's the answer..

$x {}^{2} + 4x - 21 = 0 \\ x {}^{2} + 7x - 3x - 21 = 0 \\ x (x + 7) - 3(x + 7) = 0 \\ (x + 7)(x - 3) = 0 \\ \\ (x + 7) = 0 \\ x = - 7 \\ \\ and \\ \\ (x - 3) = 0 \\ x = 3$