设X1,X2.是2X²+4x-1=0的两个根,求下列各式的值.(1)X1²+X2²; (2)1\X 1+1\X 2.希望有过程.
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![设X1,X2.是2X²+4x-1=0的两个根,求下列各式的值.(1)X1²+X2²; (2)1\X 1+1\X 2.希望有过程.](/uploads/image/z/2776691-11-1.jpg?t=%E8%AE%BEX1%2CX2.%E6%98%AF2X%26%23178%3B%2B4x-1%3D0%E7%9A%84%E4%B8%A4%E4%B8%AA%E6%A0%B9%2C%E6%B1%82%E4%B8%8B%E5%88%97%E5%90%84%E5%BC%8F%E7%9A%84%E5%80%BC.%EF%BC%881%29X1%26%23178%3B%2BX2%26%23178%3B%EF%BC%9B+%EF%BC%882%EF%BC%891%5CX+1%2B1%5CX+2.%E5%B8%8C%E6%9C%9B%E6%9C%89%E8%BF%87%E7%A8%8B.)
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设X1,X2.是2X²+4x-1=0的两个根,求下列各式的值.(1)X1²+X2²; (2)1\X 1+1\X 2.希望有过程.
设X1,X2.是2X²+4x-1=0的两个根,求下列各式的值.
(1)X1²+X2²; (2)1\X 1+1\X 2.希望有过程.
设X1,X2.是2X²+4x-1=0的两个根,求下列各式的值.(1)X1²+X2²; (2)1\X 1+1\X 2.希望有过程.
x1+x2=-2;
x1x2=-1/2;
∴(1)x1²+x2²=(x1+x2)²-2x1x2=4+1=5;
(2)1/x1+1/x2=(x1+x2)/(x1x2)=-2/(-1/2)=4;
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x1+x2=-2
x1x2=-1
所以
x1²+x2²
=(x1+x2)²-2x1x2
=4+2
=3
1/x1+1/x2
=(x1+x2)/x1x2
=2
(1)X1²+X2²=(X1+X2)²-2X1X2=(-2)²-2*(-1/2)=5
(2)1\X 1+1\X 2=(X1+X2)/X1X2=(-2)/(-1/2)=4