1. When the polynomial x ^ 2 + 6x + y ^ 2-8y + 30 has a minimum value, x =? Y =? 2. If x ^ 2 + 2x-1 = 0, then 5x ^ 2 + 10x-3 =?

1.x^2+6x+y^2-8y+30
=(x+3)²+(y-4)²+5
When x = - 3; y = 4, the original formula has a minimum value of 5
2. If x ^ 2 + 2x-1 = 0
x²=-2x+1
So 5x ^ 2 + 10x-3
=5(-2x+1)+10x-3
=-10x+5+10x-3
=2

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