Which of the following equations has only one solution?

x^2 - 1 = 0
x^2 + x = 0
x^2 + 4x + 4 = 0

What is the y-intercept of the line given by the equation

What does independent variable and dependent variable mean in math?

Aparticular telephone number is used to receive both voice calls and fax messages. suppose that 25% of the incoming calls involve fax messages, and consider a sample of 25 incoming calls. (a) what is the expected number of calls among the 25 that involve a fax message?