化简:(3x+1)+2(x^2+2x-1)-3x^2,其中x=3.
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![化简:(3x+1)+2(x^2+2x-1)-3x^2,其中x=3.](/uploads/image/z/1616816-56-6.jpg?t=%E5%8C%96%E7%AE%80%EF%BC%9A%EF%BC%883x%2B1%29%2B2%28x%5E2%2B2x-1%29-3x%5E2%2C%E5%85%B6%E4%B8%ADx%3D3.)
化简:(3x+1)+2(x^2+2x-1)-3x^2,其中x=3.
化简:(3x+1)+2(x^2+2x-1)-3x^2,其中x=3.
化简:(3x+1)+2(x^2+2x-1)-3x^2,其中x=3.
(3x+1)+2(x^2+2x-1)-3x^2
=3x+1+2x^2+4x-2-3x^2
=7x-x^2-1
当x=3时
7x-x^2-1
=21-9-1
=11
(3x+1)+2(x^2+2x-1)-3x^2,其中x=3.
=3x+1+2x^2+4x-2-3x^2
=-x^2+7x-1
=-3^2+3×7-1
=-9+21-1
=11
(3x+1)+2(x^2+2x-1)-3x^2
=3x+1+2x²+4x-2-3x²
=-3x²+2x²+3x+4x+1-2
=-x²+7x-1
=-9+21-1
=11
(3x+1)+2(x^2+2x-1)-3x^2
=3x+1-3x^2+2(x^2+2x+1)-4
=2(x+1)^2-3(x^2-x+1)
=2(x+1)^2-3(x^2-2x+1)-3x
=2(x+1)^2-3(x-1)^2-3x
=2*4^2-3*2^2-3*3
=32-12-27
=-7