已知A=x²+4x-7,B=-1/2x²-3x+5,求3(A-2B).
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已知A=x²+4x-7,B=-1/2x²-3x+5,求3(A-2B).
已知A=x²+4x-7,B=-1/2x²-3x+5,求3(A-2B).
已知A=x²+4x-7,B=-1/2x²-3x+5,求3(A-2B).
原式=3【(x²+4x-7)-2(-1/2x²-3x+5)】=3【x²+4x-7+x²+6x-10】=3【2x²+10x-17】=6x²+30x-51
A=x²+4x-7,B=-1/2x²-3x+5
3(A-2B)
=3[x²+4x-7-2(-1/2x²-3x+5)]
=3[x²+4x-7+x²+6x-10]
=6x²+30x-51
A=x²+4x-7,B=-1/2x²-3x+5,
3(A-2B)=3[x²+4x-7-2(-1/2x²-3x+5)]
=3[x²+4x-7+2x²+6x-10]
=3[3x²+10x-17]
=9x²+30x-51