Question

If $$\alpha ,\beta \in C$$   are the distinct roots, of the equation $${x^2} - x + 1 = 0,$$    then $${\alpha ^{101}} + {\beta ^{107}}$$   is equal to:

A. 0
B. 1  
C. 2
D. $$- 1$$
Answer :   1
Solution :
$$\eqalign{ & \alpha ,\beta \,\,{\text{are roots of }}{x^2} - x + 1 = 0 \cr & \therefore \,\,\alpha = - \omega \,\,{\text{and }}\beta = - {\omega ^2} \cr} $$
where $$\omega $$ is cube root of unity
$$\eqalign{ & \therefore \,\,{\alpha ^{101}} + {\beta ^{107}} = {\left( { - \omega } \right)^{101}} + {\left( { - \omega } \right)^{107}} \cr & = - \left[ {{\omega ^2} + \omega } \right] = - \left[ { - 1} \right] = 1 \cr} $$

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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