Multiply (x+1) (x+13) How do I even start this? xD

(x + 1) (x + 13)

Multiply one variable each from the first parentheses to the two variables on the second parentheses.

Ex. (1 + 2) (x + y) = 1 · x + 1 · y + 2 · x + 2 · y = 1x + 1y + 2x + 2y = 3x + 2y

So you do the same process as in the example.

(x + 1) (x + 13)

x · x + x · 13 + 1 · x + 1 · 13

x² + 13x + x + 13

= x² + 14x + 13