How do i solve 7x-y=21

Consider 6x2 + 6x + 1. which term immediately tells you that this expression is not a perfect square trinomial? justify your answer

Last year, a state university received 3,560 applications from boys. of those applications, 35 percent were from boys who lived in other states. part a)how many applications did the university receive from boys who lived in other states? part b)applications to the university from boys represented 40percent of all applications. how many applications did the university receive in all? i don't how to do part b so me and plz tell how you got your answer

Write an equation for the function that includes the points (1,4/5) and (2,2/3)