Question

(3b+7)(3b-7) = ? (podem responder com conta ? :P)

Answer 1

(3b+7).(3b-7)
9b²-21b+21b-49
9b²+0-49
9b²-49

Espero ter ajudado !

Answer 2

$(3b+7). (3b-7) \\ 9b^2-21b+21b-49 \\ 9b^2-49=0 \\ 9b^2= 49 \\ b^2= \frac{49}{9} \\ b= \sqrt{ \frac{49}{9} } \\ \\ b= \frac{7}{3}$