I need help with these, please answer all of them

Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. x^2 - 20 = x a. 5, 4 b. -5, -4 c. -5, 4 d. 5, -4

Rob spent 25%, percent more time on his research project than he had planned. he spent an extra h hours on the project. which of the following expressions could represent the number of hours rob actually spent on the project? two answers

Use the given information to determine the exact trig value. cot theta = -square root of 5 / 2 , pi/2 < theta < pi, tan theta a.) - square root of 5 / 5 c.) - 2 square root of 5 / 5 b.) - square root of 5 / 2 d.) the answer isn't d, it was incorrect