P=n2+a/n+a solve for a

What is the factored form of the following expressions? d^2 – 13d + 36

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14

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”?