Explain why the absolute value of a number will never be negative

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

Isuck at math ; ^; m a student solved this problem and said the answer is 3 feet. chase had a roll of ribbon that contained 7 7/8  feet of ribbon. he cut off one piece that was 3 5/8  feet long and another piece that was 1 1/4  feet from the roll. how much ribbon was left on the roll? is the student's answer reasonable? yes, the answer is reasonable. no, the answer is not reasonable. it should be about 2 feet. no, the answer is not reasonable. it should be about 13 feet. no, the answer is not reasonable. it should be about 4 feet.

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