4. (3x+4)(x - 2)
(3x+4)(x - 2)
If you expand this out...
The 3x has to be multiplied by both elements in the second bracket
The 4 must also be multiplied by both elements in the second bracket
(3x)(x) -2(3x) +4(x) +4(-2)
= 3x^2 -6x +4x - 8
Then you have to collect like terms (the x's)
= 3x^2 - 2x - 8
You really have to watch the signs :) Just hold onto the sign in front of the parts and pieces you are working with...