Q. 1 A5.0( 2 Votes )

# Solve the following quadratic equations by factorization method:x2 + 10ix – 21 = 0

x2 + 10ix – 21 = 0

Given x2 + 10ix – 21 = 0

x2 + 10ix – 21 × 1 = 0

We have i2 = –1 1 = –i2

By substituting 1 = –i2 in the above equation, we get

x2 + 10ix – 21(–i2) = 0

x2 + 10ix + 21i2 = 0

x2 + 3ix + 7ix + 21i2 = 0

x(x + 3i) + 7i(x + 3i) = 0

(x + 3i)(x + 7i) = 0

x + 3i = 0 or x + 7i = 0

x = –3i or –7i

Thus, the roots of the given equation are –3i and –7i.

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