Why can't x^2 - 4x + 21 be factored

If the dimensions of a rectangular prism are 5 ft x 3.5 ft x 2 ſt, what is the surface area?

Graph red beads cost $1 an ounce and gold beads cost $3 an ounce. juanita wants to purchase a 12-ounce mixture of red and gold beads that she can sell for $2 an ounce. the solution of the system shows the number of beads needed for juanita to break even. x + y = 12, x + 3y = 24 how many ounces of red beads will juanita buy to break even? how many ounces of gold beads will she buy?

My hour hand points between the 8 and the 9 in 35 minutes it will be the next hour. what time is it ?