Question

x² - 12x - 45 factorise​

Answer 1

Answer:

x²-12x-45= x²-15x+3x -45

= x(x-15) +3(x-15)

=(x-15) (x+3)

Answer 2

Factorise: x² - 12x - 45

Let us first find two numbers whose product is 45 and sum is (-12)

Since the product is negative, one number will be positive and the other number will be negative.

Since the sum is also negative, the numerically greater of the two numbers will be negative.

So there required factors are (-15) and 3.

x² - 12x - 45 = x² + (-15 + 3)x - 45

= x² - 15x + 3x - 45

= x(x - 15) +3(x - 15)

= (x - 15) (x + 3)

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