Question

find the roots of 2x^2-x-1=0​

Answer 1

Hey mate hope it helps you.

2x² - x - 1 = 0

2x² - 2x + 1x - 1 = 0

2x(x-1) + 1(x-1) = 0

(x-1)(2x + 1) = 0

x = 1 or -1/2

Answer 2

ANSWER:

• Roots of the above expression are 1 and -1/2.

GIVEN:

• 2x²-x-1 = 0

TO FIND:

• Value of the roots.

SOLUTION:

=> 2x²-x-1 = 0

=> 2x²-2x+x-1 = 0

=> (2x²-2x)+(x-1) = 0

=> 2x(x-1) +1(x-1) = 0

=> (x-1)(2x+1) = 0

Either (x-1) = 0

=> x = 1

Either (2x+1) = 0

=> 2x = -1

=> x = -1/2

Roots of the above expression are 1 and -1/2.

NOTE:

Some important formulas:

(a+b)² = a²+b²+2ab

(a-b)² = a²+b²-2ab

(a+b)(a-b) = a²-b²

(a+b)³ = a³+b³+3ab(a+b)

(a-b)³ = a³-b³-3ab(a-b)

a³+b³ = (a+b)(a²+b²-ab)

a³-b³ = (a-b)(a²+b²+ab)

(a+b)² = (a-b)²+4ab

(a-b)² = (a+b)²-4ab