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If one of the roots of a quadratic equation with rational coefficients is 2 +√3 then the qnadmtic equation is given as_________.
Question

If one of the roots of a quadratic equation with rational coefficients is 2 +√3 then the qnadmtic equation is given as_________.

A.

x2= 2 - √3

B.

x2- 4x + 1 = 0

C.

x2+ 4x - 1 = 0

D.

x2- 2 = 0​

Correct option is B

Given:
One root = 2+32 + \sqrt{3}​​

Solution:

Use the fact that for a quadratic equation with roots r1r_1​ and r2r_2​ , the equation can be written as:

(xr1)(xr2)=0(x - r_1)(x - r_2) = 0​​

Here, r1=2+3r_1 = 2 + \sqrt{3}​ and r2=23r_2 = 2 - \sqrt{3}

Multiply the factors:

(x(2+3))(x(23))=0(x - (2 + \sqrt{3}))(x - (2 - \sqrt{3})) = 0 

(x23)(x2+3)=0 (x2)2(3)2=0 (x2)23=0(x - 2 - \sqrt{3})(x - 2 + \sqrt{3}) = 0 \\ \ \\ (x - 2)^2 - (\sqrt{3})^2= 0 \\ \ \\ (x - 2)^2 - 3 = 0 ​​ ​

x24x+43=0 x24x+1=0x^2 - 4x + 4 - 3 =0 \\ \ \\ x^2 - 4x +1 = 0​​

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