(1) (9x2y3−6x3y5)÷3x2y = 9x2y3÷3x2y−6x3y5÷3x2y = 3y2−2xy4 (2) (−2x2y)3÷6x3×(−3xy2)2 = (−8x6y3)÷6x3×(9x2y4) = −68x3y3×9x2y4 = −34x3y3×9x2y4 = −12x5y7 (3) x2−17x+30 足して-17, 掛けて30になる2つの数は、-15と-2なので、
= (x−15)(x−2) (4) (x−3)(x+2)+4(x−3) = (x−3)(x+2+4) = (x−3)(x+6) (5) (3−6)2+8 = (3)2−236+(6)2+22 = 3−218+6+22 = 9−2×32+22 = 9−62+22 (6) (5−2)2−40 = (5)2−252+(2)2−210 = 5−210+2−210 = 7−410