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Lesson · Functions of several variables
A function of two variables takes a pair of inputs and gives back one number, like f(x,y)=x2+3yf(x, y) = x^2 + 3yf(x,y)=x2+3y. Think of f(x,y)f(x, y)f(x,y) as the height of a landscape above the point (x,y)(x, y)(x,y) on the ground.
To evaluate it, plug in both numbers.
Find f(−2,−1)f(-2, -1)f(−2,−1) for f(x,y)=3x2+3yf(x, y) = 3x^2 + 3yf(x,y)=3x2+3y.