I've been very confused for hours now on when to put an imfity sign when doing quadratic inequalities pls help​

Evaluate the discriminant of each equation. tell how many solutions each equation has and whether the solutions are real or imaginary. 4x^2 + 20x + 25 = 0

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.

20.ju inces. which ordered pair is a viable solution if x represents the number of books he orders and y represents the total weight of the books, in ounces? (-3,-18) (-0.5, -3) (0,0) (0.5, 3)