Are all these answers correct? samples and population in mathematics. i really need it.

Which coefficient matrix represents a system of linear equations that has a unique solution ? options in photo*

Suppose that the price p, in dollars, and the number of sales, x, of a certain item follow the equation 4 p plus 4 x plus 2 pxequals56. suppose also that p and x are both functions of time, measured in days. find the rate at which x is changing when xequals2, pequals6, and startfraction dp over dt endfraction equals1.5.

Sara has been reading about different types of financial grants, including federal pell grants, academic competitiveness grants, smart grants, and teach grants. which statement about these grants is true? filling out a fafsa will not her apply for these grants. she will not have to pay back any funds she receives from these grants. these grants only go to students with less than a 3.0 gpa. she will have to pay back all the funds she receives from these grants.