x²+2x=24
Subtract 24 to each side
x²+2x-24=24-24
x²+2x-24=0
Factor thus with
ax²+mx+nx+b
0=x²+6x-4x-24
0=x(x+6)-4(x+6)
0=(x-4)(x+6)
x-4=0
Add 4 to each side
x-4+4=0+4
x=4
x+6=0
Subtract 6 to each side
x+6-6=0-6
x=-6. As a result, x could equal to 4 and -6. Hope it help!