# How do you solve x^2=21x?

May 20, 2015

${x}^{2} = 21 x$

rewriting the equation:
${x}^{2} - 21 x = 0$

taking out the common term $x$
$x \left(x - 21\right) = 0$

equating with $0$
$x = 0 \mathmr{and} x - 21 = 0$

color(green)(x = 0 ,21 are the two solutions

May 20, 2015

${x}^{2} = 21 x$

${x}^{2} - 21 x = 0$

$x \cdot \left(x - 21\right) = 0$

$\implies {x}_{1} = 0 , {x}_{2} = 21$.