Question

5. Factorise :
@ 1-28-2+2
(i) +13r+32r + 20
(ii) x3 - 3x2 - 9x - 5
(iv) 2y3 + y2 - 2y - 1​

Answer 1

Answer:

Given :-

1) 13r + 32r + 20

2) x³ - 3x² - 9x - 5

3) 1 - 28 - 2 + 2

4) 2y³ + y² - 2y - 1

Solution :-

1) 13r + 32r + 20 = 0

➪ 13r + 32r = - 20

➪ 45r = - 20

➪ r = - 20/45

➪ r = - 4/9

∴ The answer of this question is r = - 4/9

2) x³ - 3x² - 9x - 5

➪ x³ + x² - 4x² - 4x - 5x - 5

➪ x²(x + 1) - 4x(x + 1) - 5(x + 1)

➪ (x + 1) (x² - 4x - 5)

➪ (x + 1) (x² - 5x + x - 5)

➪ (x + 1) {x(x - 5) + 1(x - 5)}

➪ (x + 1) (x - 5) (x + 1)

∴ The answer of this question is

(x + 1) (x - 5) (x + 1)

3) 1 - 28 - 2 + 2

➪ - 27 - 2 + 2

➪ - 29 + 2

➪ - 27

∴ The answer of this question is - 27

4) 2y³ + y² - 2y - 1

➪ y²(2y + 1) - 1(2y + 1)

➪ (2y + 1) (y² - 1)

➪ (2y + 1) {(y)² - (1)²}

➪ (2y + 1) (y + 1) (y - 1)

∴ The answer of this question is

(2y + 1) (y + 1) (y - 1)

Formula used :-

➪ a² - b²

➭ (a + b) (a - b)