The diagram shows a door lock.
А
B
| 3
| 4
9
The code is a letter followed by a number.
Write down all the possible codes,
write your answers like this: (A, 1)
You must write all of your answers on one line.

a complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. because no real number satisfies this equation, i is called an imaginary number. has no real solution, since the square of a real number cannot be negative.