The only one that doesn't work is number one. All you have to do is simplify the expressions and see if they are the same as -6x+8, because that is in its simplest term.
1.) -2(3x+4)
You multiply the numbers outside the parentheses into it.
-2×(3x) plus -2×4
=-6x-8 which isn't equal to 6x+8
2.)2(-3x)+2(4)= -6x+8=
3.)5(x)+5(1) is the first half which equals 5x+5.
5x+5-11x+3. Now combine like terms. Like terms are terms that have the same value of x. So 5x and -11x are like and 5 and 3 are like.
5+3+5x-11x
8-6x= -6x+8
4.)Again, combine like terms.
X-7x+2+6
-6x+8=
5.)The problem is just rearranged, the 6x is still negative and the 8 is still positive.
Hopefully this helped.