JEE Maths
JEEMathsComplex NumbersClass 11

What does “The imaginary unit” actually mean in Complex Numbers, and why does it matter for JEE?

i is defined by i² = −1, letting us handle square roots of negative numbers.

In simple words: i is defined by i² = −1, letting us handle square roots of negative numbers. Getting The imaginary unit clear matters because JEE questions on Complex Numbers usually test this idea directly, not just a formula you memorised.

Key point

The imaginary unit

Common mistake

writing √(−1)·√(−1) = √1 = 1.

Memory tip

the rule √a·√b=√(ab) fails for negatives — i² = −1, not +1.

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