已知2a-b^2=3,a+2c^2=-2,求3a+2c^2-b^2=?:4c^2+b^2
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已知2a-b^2=3,a+2c^2=-2,求3a+2c^2-b^2=?:4c^2+b^2
已知2a-b^2=3,a+2c^2=-2,求3a+2c^2-b^2=?:4c^2+b^2
已知2a-b^2=3,a+2c^2=-2,求3a+2c^2-b^2=?:4c^2+b^2
2a-b^2=3,a+2c^2=-2
3a+2c^2-b^2
=2a-b²+(a+2c²)
=3-2
=1
4c^2+b^2
=4c²+2a-2a+b²
=2(a+2c²)-(2a-b²)
=2×(-2)-3
=-7
解
2a-b²=3 ①
a+2c²=-2 ②
①+②得:
2a-b²+a+2c²=3-2=1
即
3a+2c²-b²=1
②×2得:
2a+4c²=-4 ③
③-①得:
4c²+b²=-4-3=-7