Final answer:
The sum of 1-2 and √-18 is -1 plus 3√2 * i, involving an imaginary number, which does not correspond with any of the answer choices provided.
Step-by-step explanation:
The sum of 1-2 and √-18 can be calculated as follows:
First, calculate 1-2 which yields -1.
Next, the square root of -18, √-18, involves an imaginary number since the square root of a negative number is not defined in the set of real numbers. Hence, √-18 can be rewritten as √18 * √-1. Since √-1 is represented by the imaginary unit i, we have √18 * i, which can be further simplified to 3√2 * i, as √18 equals 3√2.
So, the sum of the two values -1 and 3√2 * i is: -1 + 3√2 * i, which does not match any of the options provided in the question (a) 4.2, (b) 4/2, (c) 5/2, (d) 5√2. Thus, there seems to be an error in the question or the provided options.