Question

plz solve this question
explain by step by step​

Answer 1

Answer:

x = 2, or x = -1

Step-by-step explanation:

The method used:-

A quadratic equation is in the form of ax² + bx + c = 0

Steps to follow:

• Find two numbers p and q such that ac = pq and b = p + q

• Represent bx as px + qx i.e. Write ax² + bx + c = 0 as ax² + px + qx + c = 0

• Factorize

• Factorize further

Solution:-

x² - x - 2 = 0, here a = 1, b = -1 and c = -2

⇒x² - 2x + x - 2 = 0, now - 2 + 1 = -1 = b, also (-2)(1) = -2 = ac, hence p=-2 and q=1

⇒(x² - 2x) + (x - 2) = 0, on making groups

⇒x(x - 2) + (x - 2) = 0, on factorizing

⇒(x - 2)(x + 1) = 0, on factorizing further

⇒ x = 2, or x = -1

More things to know:-

• (a + b)² = a² + 2ab + b²

• (a - b)² = a² - 2ab + b²

• a² - b² = (a + b)(a - b)

• (a + b + c)² = a² + b² + c² + 2ab + 2bc + 2 ca

                          = a² + b² + c² + 2(ab + bc + ca)

• (a + b)³ = a³ + b³ + 3ab(a + b)

                    =  a³ + b³ + 3a²b + 3ab²

• (a - b)³ = a³ - b³ - 3ab(a - b)                    

                   = a³ - b³ - 3a²b + 3ab²  

• a³ + b³ = (a + b)(a² - ab + b²)

• a³ - b³ = (a - b)(a² + ab + b²)

• a³+b³ +c³- 3abc = (a + b + c)(a² + b² + c² - ab - bc - ca)

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