已知x=½ 求4(x+1)-7(x-1)(x+1)+3(1-x)²的值
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已知x=½ 求4(x+1)-7(x-1)(x+1)+3(1-x)²的值
已知x=½ 求4(x+1)-7(x-1)(x+1)+3(1-x)²的值
已知x=½ 求4(x+1)-7(x-1)(x+1)+3(1-x)²的值
应该第一个有个平方吧
4(x+1)²-7(x-1)(x+1)+3(1-x)²
=【4(x+1)-3(x-1)】【(x+1)-(x-1)】
=(x+7)×2
=2x+14
=1+14
=15
4(x+1)-7(x-1)(x+1)+3(1-x)²
=4x+4-7x²+7+3x²-6x+3
=-4x²-2x+14
=-4×(½)²-2×½+14
=-1-1+14
=12
4(X+1)^2-7(X-1)(X+1)+3(1-X)^2
=4x^2+8x+4-7x^2+7+3x^2-6x+3
=2x+14
=2*1/2+14
=15
15