Solve the quadratic by COMPLETING the SQUARE:

x2 + 14x - 51 = 0

Pls never taught i’m really confused and i rlly need

Question is in picture, the middle one, apologies for the others cropping into it.

Twenty tires are tested to see if they last as long as they claim they do. three tire fail the test. two tires are selected at random without replacement for a detained inspection. a. what the probability that both tires failed the test. b. what is greater the probability that the first tire passed the test and the second one failed or the probability that the first one passed and the second one passed? c. suppose 2 tires are selected at random without replacement 60 times, how can we predict the number of times both tires fail the test