x-3(7x-(x-9-3(1-2x)))
问题描述:
x-3(7x-(x-9-3(1-2x)))
答
原式=x-3{7x-[x-9-3(1-2x)]}.
=x-3{7x-[x-9-3+6x]}
=x-3[7x-(7x-12)].
=x-3(7x-7x+12).
=x-36.