Area = length *width A = x² 3x² = (x+10)(x+12) 3x² = x²+10x+12x+120 3x² = x²+22x+120 3x²-3x² = x²+22x+120-3x² 0 = -2x²+22x+120 Factor to solve for x: -2(x²-11x-60) (x+4)(x-15) x = -4 & x = 15 but we can't have a negative length so we eliminate 4. The length of the square is 15 cm.
