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大家来看看我几道数学作业.

来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/05/30 14:30:13
大家来看看我几道数学作业.
计算
(X-2Y+Z)(X+2Y-Z)
[(1/4)X-(2/5)Y]^2*[(1/4)X+(2/5)Y]^2
[(2T+1)^2-(1-2T)^2](T^2-2)
大家来看看我几道数学作业.
(X-2Y+Z)(X+2Y-Z)
=[X-(2Y-Z)][X+(2Y-Z)]
=X^2-(2Y-Z)^2
=X^2-4Y^2+4YZ-Z^2
[(1/4)X-(2/5)Y]^2*[(1/4)X+(2/5)Y]^2
=[(1/4)X]^2-[(2/5)Y]^2
=1/16X^2-4/25Y^2
[(2T+1)^2-(1-2T)^2](T^2-2)
=(2T+1+1-2T)(2T+1-1+2T)(T^2-2)
=2*4T*(T^2-2)
=8T^3-16T