TensorFlow.js: Fitting a curve to synthetic data

Original Data (Synthetic)
True coeffecients: a=-0.800, b=-0.200, c=0.900, d=0.500
Fit curve with random coefficients (before training)
Random coeffecients: a=0.887, b=0.369, c=1.000, d=0.591
Fit curve with learned coefficients (after training)
Learned coeffecients: a=-0.572, b=-0.222, c=0.781, d=0.624