1) x²+y²=14, xy=5

(x+y)²=x²+y²+2xy

14+2×5=10

=24

2) a+b=10, a²-b²=40

a²-b²=(a+b) (a-b)

40=10(a-b)

(a-b)=4

3)x²+y²=86, xy=16

(x-y)²=x²+y²-2xy

86-2×16=32

=118

Answer:

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