已知实数a,b满足(a+b)²=1,(a-b)²=25,求a²+b²+ab-15的立方根
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已知实数a,b满足(a+b)²=1,(a-b)²=25,求a²+b²+ab-15的立方根
已知实数a,b满足(a+b)²=1,(a-b)²=25,求a²+b²+ab-15的立方根
已知实数a,b满足(a+b)²=1,(a-b)²=25,求a²+b²+ab-15的立方根
a^2+2ab+b^2=1,a^2-2ab+b^2=25.所以a^2+b^2=13,ab=-6(两个式子相加相减,整体求)
所以a²+b²+ab-15=-8,立方根为-2
等会
-2,直接求解a,b的值。