Question

18) The value of (a + 3b)² + (a - 3b)² is__ *

Answer 1

Answer:

$2a^{2}+ 18b^{2}$

Step-by-step explanation:

We know that $(a+b)^{2}$ = $a^{2}+ b^{2} +2ab$

So, (a + 3b)² + (a - 3b)² = ($a^{2} + 9b^{2} +6b$ )+ ($a^{2}+ 9b^{2} -6b$)

                                     = $2a^{2}+ 18b^{2}$

Answer 2

Answer:

1

Step-by-step explanation:

(a+3b)² - (a+3b)²

a²+9b² -a² -b² - 9b²

=1