化简下列代数式5x²+4-3x²+5x-2x²-5+6x5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n第一题:当x=-3时,这个式子的值是第二题:当m=2,n=-4时,值是
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![化简下列代数式5x²+4-3x²+5x-2x²-5+6x5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n第一题:当x=-3时,这个式子的值是第二题:当m=2,n=-4时,值是](/uploads/image/z/7257074-50-4.jpg?t=%E5%8C%96%E7%AE%80%E4%B8%8B%E5%88%97%E4%BB%A3%E6%95%B0%E5%BC%8F5x%26%23178%3B%2B4%EF%BC%8D3x%26%23178%3B%2B5x%EF%BC%8D2x%26%23178%3B%EF%BC%8D5%2B6x5mn%EF%BC%8D1%2F2mn%26%23178%3B%EF%BC%8D7%2F3m%26%23178%3Bn%2B3%2F2mn%26%23178%3B%EF%BC%8D2%2F3m%26%23178%3Bn%2B2m%26%23178%3Bn%E7%AC%AC%E4%B8%80%E9%A2%98%EF%BC%9A%E5%BD%93x%3D-3%E6%97%B6%EF%BC%8C%E8%BF%99%E4%B8%AA%E5%BC%8F%E5%AD%90%E7%9A%84%E5%80%BC%E6%98%AF%E7%AC%AC%E4%BA%8C%E9%A2%98%EF%BC%9A%E5%BD%93m%3D2%EF%BC%8Cn%3D-4%E6%97%B6%EF%BC%8C%E5%80%BC%E6%98%AF)
化简下列代数式5x²+4-3x²+5x-2x²-5+6x5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n第一题:当x=-3时,这个式子的值是第二题:当m=2,n=-4时,值是
化简下列代数式
5x²+4-3x²+5x-2x²-5+6x
5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n
第一题:当x=-3时,这个式子的值是
第二题:当m=2,n=-4时,值是
化简下列代数式5x²+4-3x²+5x-2x²-5+6x5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n第一题:当x=-3时,这个式子的值是第二题:当m=2,n=-4时,值是
5x²+4-3x²+5x-2x²-5+6x
=(5x²-3x²-2x²)+(5x+6x)+(4-5)
=11X-1
当x=-3时.11X-1=11×(-3)-1=-34
5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n
=-7/3m²n-2/3m²n+2m²n+5mn-1/2mn²+3/2mn²
=mn(-7/3m-2/3m+2m+5-1/2n+3/2n)
=mn(-m+5+n)
=-mn(m-5-N)
当m=2,n=-4时,-mn(m-5-N)=-2×(-4)(2-5+4)=8
5x²+4-3x²+5x-2x²-5+6x=4+5x-5+6x=11x-1 , x=-3时, 原式=-33-1=-34
5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n=5mn-(1/2mn²-3/2mn²)-(7/3m²n-2m²n+2/3m²n)
=5mn+mn²-m²n ,m=2, n=-4时 原式=mn(5+n-m)=8
11x-1
9/3m²n+m²n+5mn
5x²+4-3x²+5x-2x²-5+6x
=5x²-3x²-2x²+5x+6x+4-5
=11X-1
5mn-1/2mn²-7/3m²n+3/2mn²-2/3m²n+2m²n
=5mn-1/2mn²+3/2mn²-7/3m²n-2/3m²n+2m²n
=5mn+mn²-m²n
1、=11x-1
2、=mn²-m²n+5mn。
1、=-33-1=-34
2、=2×16+4×4-5×2×4=8.