Question

Solve for x................

Answer 1

Choice C is correct answer.

Explanation:

Given equation is :

x²-2x-11= 0

ax²+bx+c = 0 is general quadratic equation.

x = (-b±√b²-4ac) / 2a is quadratic formula to solve quadratic equation.

Comparing general equation with given equation,we get

a = 1 , b = -2 and c = -11

Putting above values in quadratic formula ,we get

x = (-(-2)±√(-2)²-4(1)(-11)) / 2(1)

x = (2±√4+44) / 2

x = (2±√48) / 2

x = (2±4√3) / 2

x = 2(1±2√3) / 2

x = 1±2√3

Hence, the solution of x²-2x-11 =0 is 1±2√3.

Answer 2

Option C

`x={1(+/-)2√(3)}`

Explanation:

we have

`x^(2)-2x-11=0`

we know that

The formula to solve a quadratic equation of the form
`ax^(2) +bx+c=0` is equal to

`x=\frac{-b(+/-)\sqrt{b^(2)-4ac}} {2a}`

in this problem we have

`x^(2)-2x-11=0`

so

`a=1\\b=-2\\c=-11`

substitute

`x=\frac{-(-2)(+/-)\sqrt{-2^(2)-4(1)(-11)}} {2(1)}`

`x=\frac{2(+/-)√(4+44)} {2}`

`x=\frac{2(+/-)√(48)} {2}`

`x=\frac{2(+/-)4√(3)} {2}`

`x={1(+/-)2√(3)}`