What is the value of b2 - 4ac for the following equation?

2x^2 - 2x - 1 = 0​

The mean of a set of data is -3.82 and its standard deviation is 2.31. find the z score for a value of 3.99.

For one history test, keith had to answer 40 questions. of these 40 questions, keith answered 28 of them correctly. what percent did keith get on his history test? round your answer to the nearest tenth if necessary

Complete the solution of the equation. find the value of y when x equals -5. -4x - 8y = -52