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Question

Question: If the roots of the equations \(5 + 4x - 4x^{2}\) and \(x\) be real, then....

If the roots of the equations 5+4x4x25 + 4x - 4x^{2}

and xx be real, then.

A

(xa)(xb)(xc)\frac{(x - a)(x - b)}{(x - c)}

B

a>b>ca > b > c

C

a<b<ca < b < c

D

a>c<ba > c < b

Answer

a>b>ca > b > c

Explanation

Solution

Equations 13\frac{1}{3} and

23\frac{2}{3} have real roots, then from first 43\frac{4}{3}x2+x+1+2k(x2x1)=0x^{2} + x + 1 + 2k(x^{2} - x - 1) = 0 .....(i)

and from second sinA,sinB,cosA\sin A,\sin B,\cos A (for real root )

x2+2xcotB+1=0x^{2} + 2x\cot B + 1 = 0 .....(ii)

From (i) and (ii), we get result x44x3+ax2+bx+1=0x^{4} - 4x^{3} + ax^{2} + bx + 1 = 0.