필사 인증

일차항의 계수가 1이 아닌 두 일차식의 곱 (ax + b)( cx + d) = acx 2 + (ad + bc) x + bd ]ax + bg]cx + dg = acx 2 + adx + bcx + bd = acx 2 + ]ad + bcg x + bd ax b cx acx 2 bcx d adx bd (ax + b)( cx + d) = acx 2 + (ad + bc) x + bd (ax + b)( cx + d) = acx 2 + (ad + bc) x + bd (ax + b)( cx + d) = acx 2 + (ad + bc) x + bd (2x + 1)( x + 3) = 2 × 1 × x 2 + (2 × 3 + 1 × 1) x + 1 × 3 = 2x 2 + 7 x + 3 (2x + 1)( x + 3) = 2 × 1 × x 2 + (2 × 3 + 1 × 1) x + 1 × 3 = 2x 2 + 7 x + 3 (3a - 2b)( 2a + 5b) = 3 × 2 × a 2 + (3 × 5 - 2 × 2) ab + (- 2) × 5 × b 2 = 6a 2 + 11ab - 10b 2 (3a - 2b)( 2a + 5b) = 3 × 2 × a 2 + (3 × 5 - 2 × 2) ab + (- 2) × 5 × b 2 = 6a 2 + 11ab - 10b 2