Question

y² – 30y + 216 factorise​

Answer 1

Answer:

y=12,y=18

Step-by-step explanation:

y²-30y+216

y²-18y-12y+216

y(y-18)-12(y-18)

(y-12)(y-18)

y-12=0  ;  y-18=0

∴y=12 and y=18

Answer 2

Factorise: y² - 30y + 216

Let us first find two numbers whose product and 216 and sum is (-30)

Since the product is positive, therefore, either both the numbers will be positive or negative.

But the sum is negative, hence, both the numbers will also be negative.

Required factors of 216 are (-12) and (-18).

y² – 30y + 216 = y² + [(-12) + (-18)]y + 216

= y² - 12y - 18y + 216

= y(y - 12) - 18(y - 12)

= (y - 12) (y - 18)