Question

simplify the following expression.
$(3x + 7)^2$
$9x^2 + 42x + ?$

Explanation:

Step1: Recall the formula for squaring a binomial

The formula for \((a + b)^2\) is \(a^2 + 2ab + b^2\). Here, \(a = 3x\) and \(b = 7\).

Step2: Calculate the last term

We already have the first two terms \(9x^2\) (which is \(a^2=(3x)^2\)) and \(42x\) (which is \(2ab = 2\times3x\times7\)). Now we need to find \(b^2\), where \(b = 7\). So \(b^2=7^2 = 49\).

Answer:

\(49\)