题目
运用完全平方公式计算,
1.（2a+5b)^2
2.(4x-3y)^2
3.(-2m-1)^2
4.(1.5a-2/3b)^2
5.63^2
6.98^2
1.（2a+5b)^2
2.(4x-3y)^2
3.(-2m-1)^2
4.(1.5a-2/3b)^2
5.63^2
6.98^2
提问时间：2020-07-18
答案
（2a+5b)^2
=(2a)^2+(5b)^2+2*2a*5b
=4a^2+25b^2+20ab
(4x-3y)^2
=(4x)^2+(3y)^2-2*4x*3y
=16x^2+9y^2-24xy
.(-2m-1)^2
=(2m+1)^2
=(2m)^2+1+4m
=4m^2+1+4m
.(1.5a-2/3b)^2
=(3a/2-2b/3)^2
=(3a/2)^2+(2b/3)^2-2ab
=9a^2/4 +4b^2/9 -2ab
63^2
=(60+3)^2
=60^2+3^2+2*60*3
=3600+9+360
=3969
98^2
=(100-2)^2
=100^2+2^2-2*100*2
=10000+4-400
=9604
=(2a)^2+(5b)^2+2*2a*5b
=4a^2+25b^2+20ab
(4x-3y)^2
=(4x)^2+(3y)^2-2*4x*3y
=16x^2+9y^2-24xy
.(-2m-1)^2
=(2m+1)^2
=(2m)^2+1+4m
=4m^2+1+4m
.(1.5a-2/3b)^2
=(3a/2-2b/3)^2
=(3a/2)^2+(2b/3)^2-2ab
=9a^2/4 +4b^2/9 -2ab
63^2
=(60+3)^2
=60^2+3^2+2*60*3
=3600+9+360
=3969
98^2
=(100-2)^2
=100^2+2^2-2*100*2
=10000+4-400
=9604
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