已知﹙x+y-17﹚²+﹙xy-60﹚²=0 求(1) x²+y² (2)﹙x-y﹚² 帮个忙额!
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已知﹙x+y-17﹚²+﹙xy-60﹚²=0 求(1) x²+y² (2)﹙x-y﹚² 帮个忙额!
已知﹙x+y-17﹚²+﹙xy-60﹚²=0 求(1) x²+y² (2)﹙x-y﹚² 帮个忙额!
已知﹙x+y-17﹚²+﹙xy-60﹚²=0 求(1) x²+y² (2)﹙x-y﹚² 帮个忙额!
﹙x+y-17﹚²+﹙xy-60﹚²=0
所以x+y-17=0
xy-60=0
x+y=17
平方
x²+2xy+y²=289
x²+y²=289-2xy=289-120=169
(x-y)²
=x²-2xy+y²
=169-120
=49
﹙x+y-17﹚²+﹙xy-60﹚²=0
所以x+y-17=xy-60=0
所以x+y=17,xy=60
所以x^2+y^2=(x+y)^2-2xy=289-120=169
所以(x-y)^2=x^2+y^2-2xy=169-120=49