Question

y² + 3y – 18 = 0

Answer 1

Given: y² + 3y – 18 = 0
On splitting the middle term 3y as 6y – 3y, we get:
y² + 6y – 3y – 18 = 0
=> y(y + 6) – 3(y + 6) = 0
=> (y + 6) (y – 3) = 0
We know that if the product of two numbers is zero, then at least one of them must be zero.
Thus,
y + 6 = 0 or y – 3 = 0
=> y = –6 or y = 3
Therefore, the solution of the given equation is y = –6, 3.