Is (-2,1), (-1,2), (1,1), (2,3) a function?

1 Answer
Jul 7, 2015

Yes. There is no pair (a,b), (a,c) with b \ne cbc.

Explanation:

You don't need a specific function. But,
choose a model of function with 4 parameters a,b,c,d.
y = ax^3 + bx^2 + cx + dy=ax3+bx2+cx+d

1 = -8a + 4b -2c + d1=8a+4b2c+d

2 = -a + b - c + d2=a+bc+d

1 = a + b + c + d1=a+b+c+d

3 = 8a + 4b + 2c + d3=8a+4b+2c+d

If you solve this matrix, you'll find:

f(x) = 1/2x^3 -13/6x^2 - x + 11/3f(x)=12x3136x2x+113

y = (3 x^3 -13x^2 - 6x + 22)/6y=3x313x26x+226