Question

Factorise 12b+15-3b^2​

Answer 1

- 3b^2 + 12b + 15 ------------ 1)

dividing throughout equation 1) by 3.

0 = - b^2 + 4b + 5

0 = b^2 - 4b - 5

5b^2

- 5b +1b

0 = b^2 - 5b +1b - 5

0 = b^2 - 5b + 1b - 5

0 = b ( b - 5 ) + 1 ( b - 5 )

0 = ( b - 5 ) ( b + 1 )

:. ( b - 5 ) = 0 OR :. ( b + 1 ) = 0

:. b = 5 OR :. b = - 1