x^2-y^2=30,且x-y=-5,则x+y的值是多少?

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x^2-y^2=30,且x-y=-5,则x+y的值是多少?x^2-y^2=30,且x-y=-5,则x+y的值是多少?x^2-y^2=30,且x-y=-5,则x+y的值是多少?∵x^2-y^2=(x+y

x^2-y^2=30,且x-y=-5,则x+y的值是多少?
x^2-y^2=30,且x-y=-5,则x+y的值是多少?

x^2-y^2=30,且x-y=-5,则x+y的值是多少?
∵x^2-y^2=(x+y)(x-y)=30,且x-y=-5
∴x+y=30/﹣5=﹣6

x+y
=(x^2-y^2)÷(x-y)
=30÷(-5)
=-6

x^2-y^2=(x+y)(x-y)
已知:x^2-y^2=30,且x-y=-5
所以 x+y=30/-5=-6.

x^2-y^2=(x+y)(x-y)=30
用x-y=-5去替换
即-5(x+y)=30
所以x+y=-6

-6

x^2-y^2=(x+y)(x-y)=30
x+y=6/5
所以x-y
=(x^2-y^2)/(x+y)
=30÷6/5
=25

x^2-y^2=(x-y)(x+y)=30
x-y=-5
x-y=-6

6

x+y
=(x^2-y^2)÷(x-y)
=30÷(-5)
=-6

-6

-6 ,因为(x+y)乘上(x-y)等于x的平方减去y的平方

x^2-y^2=(x+y)(x-y)=30 x-y=-5 所以x+y=-6