Why would someone choose to use a graphing calculator to solve a system of linear equations instead of graphing by hand? explain your reasoning.

Which of the following expressions is equal to 2x^2+8

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).