Question

When I give answer why this will occur ? ​

Answer 1

This would have occurred because you have been trying to use some 'HTML fonts' and in applying the formula, you would have entered the wrong number of brackets which leads to this.

Answer 2

Answer:

$\Huge\sf\underline\blue{Answer}$

As :-

U may not right the latex properly!

E.g. ($&$) may be on the other line after the latex códe!