1.式子4-a²-2ab-b²的最大值是____ 2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____1.式子4-a²-2ab-b²的最大值是____2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____
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![1.式子4-a²-2ab-b²的最大值是____ 2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____1.式子4-a²-2ab-b²的最大值是____2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____](/uploads/image/z/6124262-14-2.jpg?t=1.%E5%BC%8F%E5%AD%904-a%26%23178%3B-2ab-b%26%23178%3B%E7%9A%84%E6%9C%80%E5%A4%A7%E5%80%BC%E6%98%AF____+2.%E5%B7%B2%E7%9F%A51%2Fx-1%2Fy%3D5%2Cxy%3D-1%2C%E5%88%991%2Fx%26%238308%3B-1%2Fy%26%238308%3B%3D____1.%E5%BC%8F%E5%AD%904-a%26%23178%3B-2ab-b%26%23178%3B%E7%9A%84%E6%9C%80%E5%A4%A7%E5%80%BC%E6%98%AF____2.%E5%B7%B2%E7%9F%A51%2Fx-1%2Fy%3D5%2Cxy%3D-1%2C%E5%88%991%2Fx%26%238308%3B-1%2Fy%26%238308%3B%3D____)
1.式子4-a²-2ab-b²的最大值是____ 2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____1.式子4-a²-2ab-b²的最大值是____2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____
1.式子4-a²-2ab-b²的最大值是____ 2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____
1.式子4-a²-2ab-b²的最大值是____
2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____
1.式子4-a²-2ab-b²的最大值是____ 2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____1.式子4-a²-2ab-b²的最大值是____2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=____
1.式子4-a²-2ab-b²的最大值是_4___
4-a²-2ab-b¹=4-(a+b)²;
a+b=0时,最大值=4;
2.已知1/x-1/y=5,xy=-1,则1/x⁴-1/y⁴=±115√21____
(1/x+1/y)²=(1/x-1/y)²+4/xy=25-4=21;
1/x+1/y=±√21;
1/x⁴-1/y⁴=(1/x²+1/y¹)(1/x²-1/y²)=((1/x-1/y)²+2/xy)(1/x+1/y)(1/x-1/y)=23×(±√21)×5=±115√21;
1.最大是4,4-(a+b)²
2.(1/x-1/y)⁴分解一下,具体忘记了,到这你该会了吧
4-a²-2ab-b²=4-(a+b)²≤4,式子4-a²-2ab-b²的最大值是4 1/x⁴-1/y⁴=(1/x²+1/y²)(1/x-1/y)(1/x+1/y) =5[(1/x-1/y)²+2/xy](1/x+1/y) =5(25-2)((1/x+1/y) =±115√[(1/x-1/y)²+4/xy] =±115√21