Find the roots of the equation below. 7x2+1=0

Roots of the equation 7x²+1=0: 

7x²+1=0, now we transfer 1 to the right:

7x²=-1, divide by 7:

x²=-1/7, take the square root:

x=+/-√(-1/7)=+/-(i/√7), now we multiply the numerator and the denominator by √7, and we see that we have two complex roots:

x=+/-(i√7)/(√7*√7)=+/-(i√7)/7

We have two possible roots:

x₁=+(i√7)/7 and x₂=-(i√7)/7, so the correct answer is the last one on the image:

x₁,₂=+/-(i√7)/7.