Question

Por Favor! Alguém me ajuda.

Answer 1

Answer:

The answer is A.

Step-by-step explanation:

You have to apply :

${(a - b)}^{2} ⇒ {a}^{2} - 2ab + {b}^{2}$

So for this question :

${(3a - b)}^{2}$

$= {(3a)}^{2} - 2(3a)(b) + {(b)}^{2}$

$= 9 {a}^{2} - 6ab + {b}^{2}$