Expand (2[x+3])²: Solving a Double Bracket Square Expression

Question

$(2\lbrack x+3\rbrack)^2=$

00:00 Simply

00:03 Let's open parentheses properly, multiply by each factor

00:15 We'll use shortened multiplication formulas to open the parentheses

00:40 We'll solve the squares and multiplications

00:53 And this is the solution to the question

We will first solve the exercise by opening the inner brackets:

(2[x+3])²

(2x+6)²

We will then use the shortcut multiplication formula:

(X+Y)²=X²+2XY+Y²

(2x+6)² = 2x² + 2x*6*2 + 6² = 2x+24x+36

$4x^2+24x+36$