John is j years old the product of his younger brothers and older sisters age is j^2-2j-15 how old are Jones, brother and sister, in terms of Jones age

Answer 1

Factorisation.

j² - 2 j - 15 = j² + 3 j - 5 j - 15 =

( j² + 3 j ) - ( 5 j - 15 ) =

j ( j + 3 ) - 5 ( j + 3 ) =

( j + 3 ) ( j - 5 ) =

( j - 5 ) ( j + 3 )

Brother is 5 yrs younger, sister u 3 yrs older.

Answer 2

My typo in second line.

j² + 3 j - 5 j - 15 is not

( j² + 3 j ) - ( 5 j - 15 )

j² + 3 j - 5 j - 15 = ( j² + 3 j ) - ( 5 j + 15 )