Question

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

Answer 1

Answer:

Option C

$x={1(+/-)2\sqrt{3}}$

Step-by-step 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

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

$x=\frac{2(+/-)\sqrt{4+44}} {2}$

$x=\frac{2(+/-)\sqrt{48}} {2}$

$x=\frac{2(+/-)4\sqrt{3}} {2}$

$x={1(+/-)2\sqrt{3}}$

Answer 2

Answer:

Choice C is correct answer.

Step-by-step 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.