Answer
See the picture.
Now, the slope of the lines changes as $x_2$, in first case, or $x_1$, in the second case, change.
Work Step by Step
$ŷ=6-0.3x_1+1.7x_2+0.04x_1x_2$
- For $x_2=10$:
$ŷ=6-0.3x_1+1.7\times10+0.04x_110=23+0.1x_1$
- For $x_2=20$:
$ŷ=6-0.3x_1+1.7\times20+0.04x_120=40+0.5x_1$
- For $x_2=30$:
$ŷ=6-0.3x_1+1.7\times30+0.04x_130=57+0.9x_1$
- For $x_1=40$:
$ŷ=6-0.3\times40+1.7x_2+0.04\times40x_2=-6+3.3x_2$
- For $x_1=50$:
$ŷ=6-0.3\times50+1.7x_2+0.04\times50x_2=-9+3.7x_2$
- For $x_1=60$:
$ŷ=6-0.3\times60+1.7x_2+0.04\times60x_2=-12+4.1x_2$
