Question

If $$\alpha ,\beta $$  are real and $${\alpha ^2},{\beta ^2}$$  are the roots of the equation $${a^2}{x^2} - x + 1 - {a^2} = 0\left( {\frac{1}{{\sqrt 2 }} < a < 1} \right)$$       and $${\beta ^2} \ne 1,{\text{then }}{\beta ^2} = $$

A. $$a^2$$
B. $$\frac{{1 - {a^2}}}{{{a^2}}}$$  
C. $${1 - {a^2}}$$
D. $${1 + {a^2}}$$
Answer :   $$\frac{{1 - {a^2}}}{{{a^2}}}$$
Solution :
$$\eqalign{ & {\alpha ^2} + {\beta ^2} = \frac{1}{{{a^2}}}\,\,{\text{and }}{\alpha ^2}{\beta ^2} = \frac{{1 - {a^2}}}{{{a^2}}} \cr & \Rightarrow {\alpha ^2} + {\beta ^2} - 1 = {\alpha ^2}{\beta ^2} \cr & \Rightarrow \left( {{\alpha ^2} - 1} \right)\left( {{\beta ^2} - 1} \right) = 0 \cr & \because {\beta ^2} \ne 1, \cr & \Rightarrow {\alpha ^2} = 1,\,\,{\text{so,}}\,\,{\beta ^2} = \frac{{1 - {a^2}}}{{{a^2}}} \cr} $$

Releted MCQ Question on
Algebra >> Quadratic Equation

Releted Question 1

If $$\ell ,m,n$$  are real, $$\ell \ne m,$$  then the roots by the equation: $$\left( {\ell - m} \right){x^2} - 5\left( {\ell + m} \right)x - 2\left( {\ell - m} \right) = 0$$         are

A. Real and equal
B. Complex
C. Real and unequal
D. None of these
Releted Question 2

The equation $$x + 2y + 2z = 1{\text{ and }}2x + 4y + 4z = 9{\text{ have}}$$

A. Only one solution
B. Only two solutions
C. Infinite number of solutions
D. None of these
Releted Question 3

Let $$a > 0, b > 0$$    and $$c > 0$$ . Then the roots of the equation $$a{x^2} + bx + c = 0$$

A. are real and negative
B. have negative real parts
C. both (A) and (B)
D. none of these
Releted Question 4

Both the roots of the equation $$\left( {x - b} \right)\left( {x - c} \right) + \left( {x - a} \right)\left( {x - c} \right) + \left( {x - a} \right)\left( {x - b} \right) = 0$$           are always

A. positive
B. real
C. negative
D. none of these.

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Quadratic Equation


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