(紧急)数学题:已知a²+2a+b²-4b+5=0,求2a²+4b-3的值
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![(紧急)数学题:已知a²+2a+b²-4b+5=0,求2a²+4b-3的值](/uploads/image/z/2590408-64-8.jpg?t=%EF%BC%88%E7%B4%A7%E6%80%A5%EF%BC%89%E6%95%B0%E5%AD%A6%E9%A2%98%EF%BC%9A%E5%B7%B2%E7%9F%A5a%26%23178%3B%2B2a%2Bb%26%23178%3B-4b%2B5%3D0%2C%E6%B1%822a%26%23178%3B%2B4b-3%E7%9A%84%E5%80%BC)
(紧急)数学题:已知a²+2a+b²-4b+5=0,求2a²+4b-3的值
(紧急)数学题:已知a²+2a+b²-4b+5=0,求2a²+4b-3的值
(紧急)数学题:已知a²+2a+b²-4b+5=0,求2a²+4b-3的值
a²+2a+b²-4b+5=0
(a²+2a+1)+(b²-4b+4)=0
(a+1)²+(b-2)²=0
a+1=0, b-2=0
a=-1, b=2
2a²+4b-3
=2×1+8-3
=7
原式 =(a+1)^2+(b-2)^2=0
所以a=-1,b=2
即2a^2+4b^2-3=2+16-3=15
a²+2a+b²-4b+5=0
(a²+2a+1)+(b²-4b+4)=0
(a+1)²+(b-2)²=0
a+1=0,b-2=0
a=-1,b=2
2a²+4b-3
=2×(-1)²+4×2-3
=2+8-3
=7
原等式即(a-1)²+(b-4)²=0,所以a=1,b=4,原式=15