The difference between three times a number and 10 is 17

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Ron has 8 caps and 4 of his caps are blue. thes rest of his cap are red. how many of ron's caps are red

Given the expression (7 ? 4i) ? (2 + 6i), perform the indicated operation and write the answer in the form a + bi.