Binomial expressions

Expand the following:
(3 x+4) (x-1)

(3 x+4) (x-1) = (3 x) (x) + (3 x) (-1) + (4) (x) + (4) (-1):
3 x x+4 x-3 x-4

3 x x = 3 x^2:
3 x^2+4 x-3 x-4

4 x-3 x = x:
Answer: |  3x^2 + x - 4

$\color{red}(3x+4)(x-1)$

= $\color{orange}3x(x-1)+4(x-1)$<--- Multiplication Distributive Law

=$\color{lime}(3x)(x)-(3x)(1)+4x-4$ <--- Multiplication Distributive Law again

= $\color{blue}3x^2-3x+4x-4$<--- Multiplying out the brackets.

= $\color{purple}3x^2+x-4$<--- Combining like terms. Finish.