Question

40 - 18 x minus x square is equal to​

Answer 1

Answer:

(x + 2)(x - 20)

Step-by-step explanation:

Given : 40 - 18x - x²

Rearranging it, we get

→ x² - 18x - 40

On comparing this with ax² + bx + c, we get

a = 1, b = - 18, c = - 40

By Middle Term Factorisation,

→ x² - 20x + 2x - 40

Taking out common terms, we get

→ x(x - 20) + 2(x - 20)

→ (x + 2)(x - 20)

• In Middle Term Factorisation, we factorise the middle term only.
• First we multiply 'a' and 'c'.
• Then we have to find such a pair of number such that on addition or subtraction, the result equals to 'b' and on multiplication, the result equals to the multiplication of 'a' and 'c'.

We get the two terms : 2 and - 20

Addition = (2) + (- 20) = - 18 = b

Multiplication = (2)(- 20) = - 40 = Product of 'a' and 'c' i.e. (1)(- 40) = - 40