-3(x-8)=-3x-24错在哪里?
括号前是负号,去括号后,括号内每一项都要改变符号,
∴-3(X-8)=-3X+24.
2(4x-1) -3(1-1/6x)
=8X-2 =-3+1/2X
2(2a-3b)-(3a-2b)
=4a-6b-3a+2b
=a-4b,
3x的平方-[7x-2(4x-3)-2x的平方]
=3X^2-[7X-8X+6-2X^2]
=3X^2-[-X+6-2X^2]
=3X^2+X-6+2X^2
=5X^2+X-5.
-3(x-8)=-3x-24错在哪里?
括号前是负号,去括号后,括号内每一项都要改变符号,
∴-3(X-8)=-3X+24.
2(4x-1) -3(1-1/6x)
=8X-2 =-3+1/2X
2(2a-3b)-(3a-2b)
=4a-6b-3a+2b
=a-4b,
3x的平方-[7x-2(4x-3)-2x的平方]
=3X^2-[7X-8X+6-2X^2]
=3X^2-[-X+6-2X^2]
=3X^2+X-6+2X^2
=5X^2+X-5.