What is (1+2j) + (1+3j)? Your answer should contain three significant figures.

do you mean

(1i+2j) + (1i+3j) ?
2.00 i + 5.00 j

I don't know. That is just what thequestion ask and I don't get it.

To find the sum of two complex numbers, you simply add the real parts and add the imaginary parts separately.

In this case, we have:
(1 + 2j) + (1 + 3j)

The real parts are 1 and 1, so we add them together: 1 + 1 = 2

The imaginary parts are 2j and 3j, so we add them together: 2j + 3j = 5j

Putting it all together, the sum of (1 + 2j) + (1 + 3j) is 2 + 5j.

Therefore, the answer is 2 + 5j, which is the sum of the two given complex numbers.