Find the `y`-intercept of `f(x)` = `4 x -21 + x^2`

Enter your answer as an ordered pair.

Box 1: Enter your answer as an n-tuple of numbers. Example: (2,5.5172)
Enter each value as a number (like 5, -3, 2.2172) or as a calculation (like 5/3, 2^3, 5+4)
Enter DNE for Does Not Exist, oo for Infinity