Question

A = {xeN, x2 + 4 = 0}. Then A=?
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Answer 1

Heya

A = { x : x€ N, x² + 4x = 0 }

x² = -4

x = ±2√-1

x = ±2i

Here, is no value of x ( x€N ) which will satisfy this Equation ( x = ±2i ) .

So, Set A is An empty set.. or null set or void set.