What is x+y+4x-3x+2y+ 3y

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Rewrite the following quadratic functions in intercept or factored form. show your work. f(t) = 20t^2 + 14t - 12

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x