已知x^2+3x+7=8,求代数式 3x^2+9x-9 的值另一道题已知x/y = 5/3 ,求x/(x+y) = x/(x-y) - y^2/(x^2-y^2)的值求详细步骤谢谢
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已知x^2+3x+7=8,求代数式 3x^2+9x-9 的值另一道题已知x/y = 5/3 ,求x/(x+y) = x/(x-y) - y^2/(x^2-y^2)的值求详细步骤谢谢
已知x^2+3x+7=8,求代数式 3x^2+9x-9 的值
另一道题
已知x/y = 5/3 ,求x/(x+y) = x/(x-y) - y^2/(x^2-y^2)的值
求详细步骤谢谢
已知x^2+3x+7=8,求代数式 3x^2+9x-9 的值另一道题已知x/y = 5/3 ,求x/(x+y) = x/(x-y) - y^2/(x^2-y^2)的值求详细步骤谢谢
x^2+3x+7=8
x^2+3x=1
3x^2+9x-9
=3(x^2+3x)-9
=3-9
=-6
x/(x+y) = x/(x-y) - y^2/(x^2-y^2)
这个是等吗
已知x^2+3x+7=8,,
x^2+3x=1
代数式 3x^2+9x-9 的值
=3(x^2+3x)-9
=3*1-9
=-6
已知x/y = 5/3 ,
x/(x+y) + x/(x-y) - y^2/(x^2-y^2)的值
=(x(x-y)+x(x+y))/(x+y)(x-y) - y^2/(x^2-y^2)
=2x^2...
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已知x^2+3x+7=8,,
x^2+3x=1
代数式 3x^2+9x-9 的值
=3(x^2+3x)-9
=3*1-9
=-6
已知x/y = 5/3 ,
x/(x+y) + x/(x-y) - y^2/(x^2-y^2)的值
=(x(x-y)+x(x+y))/(x+y)(x-y) - y^2/(x^2-y^2)
=2x^2/(x^2-y^2) - y^2/(x^2-y^2)
=(2x^2-y^2)/(x^2-y^2)
=(2(x/y)^2-1)/((x/y)^2-1)
=(2*(5/3)^2-1)/((5/3)^2-1)
=(50/9-1)/(25/9-1)
=41/16
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