Ineed adding polynomials like -p+4 and 5p^2 - 2p +2

At which value in the domain does f(x) =0?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

Solve for x where 0 equation: cot^2x+2cotx+1=0