Just plug in the values ( x , y ) = ( − 1.02 , 0.97 ) {\displaystyle \displaystyle (x,y)=(-1.02,0.97)} into f ( x , y ) ≈ − 1 − 3 2 ( y − 1 ) {\displaystyle \displaystyle f(x,y)\approx -1-{\frac {3}{2}}(y-1)}
