课后习题(A组)一、想一想,填一填(1)(a+1)(-a-1)=_____________(2)(x²-2y²)²=_____________(3)(3\5x+____)²=9\25x²+6xy+25y²(4)m²-8m+_____=(m-________)²(5)(-a-2b)²=______________(6)(2a+b)²=4a²+_______+b²二、利用完全平方公式计算:(1)(7x+2)²(2)(-1+2ab)²(3)(-3a-4b)²(4)(2a-b)²-2b²(5)(a+b-2c)²三、解答:(1)已知x²+y²=15,xy=3,求(x-y)²的值。(2)已知(a-b)²=9,ab=1,求a²+b²以及(a+b)²的值。B组一、填空:(1)(a+1\2)²(a-1\2)²=______________(2)9x²+_______+4y²=(___________)²(3)x²+1\x²=(x+1\x)²-_______=(x-1\x)²+__________(4)已知x²+y²=25,x+y=7,且x>y,则x-y的值等于_________二、利用公式计算:(1)(m+1)²(m-1)²(2)(2x-3y-1)(2x+3y-1)三、已知(a-b)²=7,(a+b)²=13,试求a²+b²和ab的值。四、解不等式:(2x-5)²+(3x+1)²>13(x²-10)+2答案A组一、(1)-a²-2a-1(2)x--4x²y²+4y(3)5y(4)16,4(5)a²+4ab+4b²(6)4ab二、解:(1)(7x+2)²=(7x)²+2*(7x)*2+2²=49x²+28x+4(2)(-1+2ab)²=(-1)²+2*(-1)*(2ab)+(2ab)²=4a²b²-4ab+1(3)(-3a-4b)²=[-(3a+4b)]²=(3a+4b)²=9a²+24ab+16b²(4)(2a-b)²-2b²=(2a)²-2*(2a)*b+b²-2b²=4a²-4ab-b²(5)(a+b-2c)²=(a+b)²-2*(a+b)*(2c)+(2c)²=(a+b)²-4ac-4bc+4c²=a²+b²+4c²+2ab-4ac-4bc三、解:(1)(x-y)²=x²-2xy+y²因为x²+y²=15,xy=3所以原式=x²+y²-2xy=15-6=9(2)因为(a-b)²=a²-2ab+b²=9,ab=1所以a²+b²=9+2ab=9+2=11(a+b)²=a²+2ab+b²=11+2=13B组一、(1)a-a²\2+1\16(2)12xy或-12xy(3x+2y)²或(3x-2y)²(3)22(4)1二、解:(1)原式=m-2m²+1(2)原式=4x²-9y²-4x+1三、解:101.5四、解:4020025牛心中心学校王艳梅4444