千味辛
幼苗
共回答了21个问题采纳率:95.2% 举报
(1/2x的2方+1/3)(1/2x的2方-1/3)=(1/2x)^2-(1/3)^2=1/4x^2-1/6
(-2x-3y)(-2x+3y)=(-2x)^2-(3y)^2=4x^2-9y^2
(-2a-3b)(2a-3b)=(-3b)^2-(2a)^2=9b^2-4a^2
(a+2)(a-2)(a的2方+4)==(a^2-b^2)(a^2+b^2)=a^4-b^4
(1/9y的2方+x的2方)(1/3y-x)(1/3y+x)==(1/9y^2+x^2)(1/9y^2-x^2)=1/81y^4-x^4
简便计算103乘97=(100+3)(100-3)=100^2-3^2=10000-9=99991
79乘81=(80-1)(80+1)=80^2-1^2=6400-1=6399
50.2乘49.8=(50+0.2)(50-0.2)=50^2-0.2^2=2500-0.04=2499.96
10又1/7乘9又6/7=(10+1/7)(10-1/7)=10^2-(1/7)^2=100-1/49=99+48/49=99又48/49
(a-b)(a+b)-(a+3b)(a-3b)=a^2-b^2-a^2+9b^2=8b^2
(x-2y)(x+2y)+(2x-y)(2x+y)=x^2-4y^2+4x^2-y^2=5x^2-5y^2
(x的2方+2)(x的2方-2)-(x-2)(x+2)=x^4-2^2-x^2+2^2=x^4-x^2
1年前
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