How do i answer these maths questions?

(1). Use grad = (difference in ys)/(difference in xs) for CD; grad =( k - -1)/(5 - 2) =2 and solve for k >> 5. (2). Factorise then consider the product of the two brackets. To be less than 0 the product must be negative so either (- ) x ( + ) or ( + ) x ( - ). ie what range of each bracket works? Here (2x +1)(x + 3) < 0 , for 1st negative for x < -1/2, 2nd positive for x> -3 so product will be neg for -3-1/2 and 2nd negative for x<-3 so product will be neg for these disjoint ranges too. Hope that helps? It's easier to visualise if you draw the number lines.