The arithmetic sequence a sub i is defined by the formula a sub 1 =-4910 a sub i-1 +8 find the sum of the first 575 terms in the sequence

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.