7^4-3x7^2-8x7^3化简
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/11 03:29:45
7^4-3x7^2-8x7^3化简
(x+y)^2-2(x^2-y^2)+(x-y)^2其中x=15分之2Y=3分1
以知M+N=9,MN=14求M^2-MN+N^2的值
(x+y)^2-2(x^2-y^2)+(x-y)^2其中x=15分之2Y=3分1
以知M+N=9,MN=14求M^2-MN+N^2的值
7^4-3x7^2-8x7^3
=7^2x(7^2-3-8x7)
=7^2x(49-3-56)
=49x(-10)
=-490
(x+y)^2-2(x^2-y^2)+(x-y)^2
=(x+y)^2-2(x+y)(x-y)+(x-y)^2
=[(x+y)-(x-y)]^2
=4y^2
=4/9
M^2-MN+N^2
=M^2+2MN+N^2-3MN
=(M+N)^2-3MN
=9^2-3*14
=39
=7^2x(7^2-3-8x7)
=7^2x(49-3-56)
=49x(-10)
=-490
(x+y)^2-2(x^2-y^2)+(x-y)^2
=(x+y)^2-2(x+y)(x-y)+(x-y)^2
=[(x+y)-(x-y)]^2
=4y^2
=4/9
M^2-MN+N^2
=M^2+2MN+N^2-3MN
=(M+N)^2-3MN
=9^2-3*14
=39
7^4-3x7^2-8x7^3化简
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