Alec simplified the expression below. He then checked his work by substituting 3 for x. He noticed his two values were not equal. The expression gave him an answer of 27, and the simplified expression gave him an answer of 28.
What was Alec's error when simplifying?

Find the length of the following tangent segments to the circles centered at o and o' whose radii are 5 and 3 respectively and the distance between o and o' is 12. what is the tangent segment of cd?

What is the value of x in the equation7x+2y=48 when y=3

1. suppose that scores on a knowledge test are normally distributed with a mean of 71 and a standard deviation of 6. a. label the curve: show the mean and the value at each standard deviation: b. if angelica scored a 76 on the test, what is her z-score? (draw her score on the curve above and label) c. what percent of students did angelica score higher than? how can you tell? d. if 185 students took the test, how many students scored higher than angelica?