Important Questions of Complex Numbers and Quadratic Equations Mathematics | Zigya

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141.

The number of solution(s) of the equation x + 1 - x - 1 = 4x - 1 is/are

  • 2

  • 0

  • 3

  • 1


142.

The value of z2 + z - 32 + z - i2 is minimum when z equals

  • 2 - 23i

  • 45 + 3i

  • 1 + i3

  • 1 - i3


143.

The solution of the equation log101log7x + 7 + x = 0 is

  • 3

  • 7

  • 9

  • 49


144.

In a ABCtanA and tanB are the roots of pq(x2 + 1) = r2x. Then, ABC is

  • a right angled triangle

  • an acute angled triangle

  • an obtuse angled triangle

  • an equilateral triangle


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145.

Let f(x) = 2x+ 5x + 1. If we write f(x) as f(x) = a(x + 1)(x - 2) + b(x - 2)(x - 1) + c(x - 1)(x + 1) for real numbers a, b, c then

  • there are infinite number of choices for a, b, c

  • only one choice for a but infinite number of choices for b and c

  • exactly one choice for each of a, b, c

  • more than one but finite number of choices for a, b, c


146.

If α, β are the roots of ax2 + bx + c = 0 (a  0) and α + h, β + h are the roots of px2 + qx + r = 0 (p  0), then the ratio of the squares of their discriminants is

  • a2 : p2

  • a : p2

  • a2 : p

  • a : 2p


147.

Suppose that z1, z2, z3 are three vertices of an equilateral triangle in the Argand plane. Let α = 123 + i and β be a non-zero complex number. The points αz1 + β, αz2 + β, αz3 + β will be

  • the vertices of an equilateral triangle

  • the vertices of an isosceles triangle 

  • collinear

  • the vertices of a scalene triangle


148.

In the Argand plane, the distinct roots of 1 + z + z3 + z4 = 0 (z is a complex number) represent vertices of

  • a square

  • an equilateral triangle

  • a rhombus

  • a rectangle


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149.

Let α, β be the roots of x2 - x - 1 = 0 and Sn = αn + βn, for all integers n  1. Then, for every integer n  2

  • Sn + Sn - 1 = Sn +1

  • Sn - Sn - 1 = Sn +1

  • Sn - 1 = Sn +1

  • Sn + Sn - 1 = 2Sn +1


150.

If α, β are the roots of the quadratic equation x2 + px + q = 0, then the values of α3 + β3 and α4 + α2β2 + β4 are respectively

  • 3pq - p3 and p4 - 3p2q + 3q2

  • - p(3q - p2) and (p2 - q)(p2 + 3q)

  • pq - 4 and p4 - q4

  • 3pq - p3 and (p2 - q)(p2 - 3q)


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