12. * 1 point in the equation, y =x*tc a) c1s known as the variable andx and y are known as parameters (6) c is known as the parameter and x and y are known as

12. * 1 point In the equation, y =x*tc a) c1s known as the variable andx and y are known as parameters (6) c is known as the parameter and x and y are known as the main variables (C)c and x are known as the parameters and y is known as the main variable (d) none of the above O O b Oc O d 28. 1 point For function fxy) to have minimum value at (a,b) value is? a) rt-s2>0 and r<0 (6) rt-s2>0 and r>0 (C) rt-s2<0 and r0 and r>0 O a O b O c Od