It looks like it was most likely Rafael Bombelli in 1572, from what I can find. I've posted a related link to a Wikipedia article. Wikipedia should not be your sole source of information, but it's a starting point.
Rene Descartes came up with the word imaginary in 1637 to describe them. It was a derogatory term. He (and many other mathematicians of that age) did not like imaginary numbers. Many people didn't believe in them, because they were not real.
Term- a number, a variable, or a product of numbers and variables.
The set of real numbers.
Composite numbers are the numbers that have more than two factors.
There is no such formula. Rectangular numbers are composite numbers and there is no known formula that will generate either composite numbers or prime numbers.
Rene Descartes came up with the word imaginary in 1637 to describe them. It was a derogatory term. He (and many other mathematicians of that age) did not like imaginary numbers. Many people didn't believe in them, because they were not real.
the equator
Complex numbers are numbers of the a + bi where a and b are real number and i is the imaginary square root of -1.
They are prime numbers.
Iron Curtain
An imaginary number is a number, which when squared, gives a negative real number. Any positive or negative real number, when squared, will give a positive real number. Imaginary numbers were originally conceived (around the 1500's) to provide solutions to equations which required there be a solution to the square root of a negative real number. Originally, that was the only purpose that they served, so they were given the term imaginary. The imaginary numbers were shown to be graphically at a 90° angle to real numbers. Complex numbers are the combination of real and imaginary numbers, and can be plotted graphically on a complex plane, just like you would plot x and y coordinates on a regular 2-dimensional plane.Through the work of Euler in the 1700's and others, a relationship between imaginary numbers and the behavior of waves and oscillating motion was worked out. See related link for some interesting information about imaginary and complex numbers.
That's difficult to say. Rafael Bombelli defined an imaginary number in 1572, but Rene Descartes actually gave the term imaginary. Nobody seemed to have much use for them until the work of Euler and Gauss in the 1700's and 1800's. This information I got from the Wikipedia article on Imaginary Numbers.
The Iron Curtain. He used the term in a speech in Fulton Missouri in 1946.
Digital
"Single digit numbers".
The term social scientists use to describe the power of a first impression to influence subsequent perceptions is?
Each term is a square or triangular number. In the context of the sequence of square numbers, the first term is the first square number, the second term is the second square number and so on.