solve:2(x+y)=xy, xy+yz+zx=108, xyz=180
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Answered by
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Given, x+y+z=8,xy+yz+zx=20
Now, x
3
+y
3
+z
3
−3xyz=(x+y+z)(x
2
+y
2
+z
2
−xy−yz−zx)
Again, (x+y+z)
2
=x
2
+y
2
+z
2
+2xy+2yz+2zx
x
2
+y
2
+z
2
=(x+y+z)
2
−2(xy+yz+zx)
x
2
+y
2
+z
2
=(8)
2
−2(20)=24
x
3
+y
3
+z
3
−3xyz=(x+y+z)[x
2
+y
2
+z
2
−(xy+yz+zx)]
x
3
+y
3
+z
3
−3xyz=(8)[24−(20)]
x
3
+y
3
+z
3
−3xyz=(8)[24−(20)]=8(4)=32
hope it helps you ☺️
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