Solve the following quadratic equation: x2 + 3ix + 10 = 0 - Mathematics and Statistics

Sum

x2 + 3ix + 10 = 0

Solution

Given equation is x2 + 3ix + 10 = 0
Comparing with ax2 + bx + c = 0, we get
a = 1, b = 3i, c = 10
Discriminant = b2 – 4ac

= (3i)2 – 4 x 1 x 10

= 9i2 – 40

= – 9 – 40      ...[∵ i2 = – 1]

= – 49 < 0
So, the given equation has complex roots.
These roots are given by

x = (-"b" ± sqrt("b"^2 - 4"ac"))/(2"a")

= (-3"i" ± sqrt(-49))/(2(1)

∴ x = (-3"i" + 7"i")/2

∴ x = (-3"i" + 7"i")/2 or x = (-3"i" - 7"i")/2

∴ x = 2i or x = – 5i
∴ the roots of the given equation are 2i and – 5i.

Concept: Solution of a Quadratic Equation in Complex Number System
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