x2+2x+13=0
Multiplying by 3 throughout,
3x2+6x+1=0
Multiplying by 3 throughout to make the
co−efficient of x2, a perfect square,
9x2+18x+3=0
(3x)2+2×3x×3+(3)2−(3)2+3=0
(3x+3)2−6=0
3x+3=√6 or 3x+3=−√6
Therefore,
x=(√6−3)3 or x=(−√6−3)3
x=√2√3−1 or x=−√2√3−1