# Step-by-step Solution

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## Step-by-step explanation

Problem to solve:

$\left(a+3b\right)\left(a-3b\right)$

Learn how to solve special products problems step by step online.

$a^2-\left(3b\right)^2$

Learn how to solve special products problems step by step online. Solve the product (a+3b)(a-3b). The sum of two terms multiplied by their difference is equal to the square of the first term minus the square of the second term. In other words: (a+b)(a-b)=a^2-b^2, where:<ul><li>The first term (a) is a.</li><li>The second term (b) is 3b.</li></ul>Then:. The power of a product is equal to the product of it's factors raised to the same power. Calculate the power 3^2. Multiply -1 times 9.

$a^2-9b^2$
$\left(a+3b\right)\left(a-3b\right)$