for ax2+bx+c find two numbers n,m, that m*n = a*c and m+n = b </span><span><span> 3x^2 - 2x - 8 a=3, b=-2, c=-8 </span>a*c = 3*(-8) = -24 -24=(-6)*4 and -6+4=-2, so m=-6 and n=4
replace bx with mx + nx and factor by grouping </span><span> 3x^2 - 2x - 8 = </span>3x^2 -6x + 4x -8 = 3x(x-2) + 4(x-2) = (3x+4)(x-2)