Don't know this please me

Solve each quadratic equation by factoring and using the zero product property. n^2 - 49 = 0

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.

Find the percent cost of the total spent on each equipment $36, fees $158, transportation $59 a. 14%, 62%, 23% b. 15%, 60%, 35% c. 10%, 70%, 20% d. 11%, 62%, 27%