MTB > LET 'WEIGHT' = 3.1415927 * C1 * C1 * C2 * 1
MTB >
MTB > NOTEWEIGHT = PI * RADIUS * RADIUS * LENGTH * DENSITY
MTB > PRINT C1 C2 C200

ROWRADIUSLENGTHWEIGHT

1 0.49 1.8 1.35773
2 0.49 2.2 1.65945
3 0.51 1.8 1.47083
4 0.51 2.2 1.79768
5 0.50 2.0 1.57080
6 0.48 2.0 1.44765
7 0.52 2.0 1.69897
8 0.50 1.6 1.25664
9 0.50 2.4 1.88496

MTB > NOTENOW, TO OBTAIN THE TWO REGRESSION EQUATIONS:
MTB >
MTB > LET C11=C1*C1
MTB > LET C12=C1*C2
MTB > LET C22=C2*C2
MTB >
MTB > REGRESS C100 5 C1 C2 C11 C22 C12

The regression equation is
RESISTOR = 3068 - 12266 RADIUS + 1529 LENGTH + 12259 C11 + 0.01 C22
- 2039 C12

PredictorCoefStdevt-ratiop
Constant3067.7112.027.380.000
RADIUS-12265.9419.8-29.220.000
LENGTH1528.8818.9480.730.000
C1112259.5413.229.670.000
C220.0101.0330.010.993
C12-2038.8436.96-55.160.000

s = 0.1478R-sq = 100.0%R-sq(adj) = 100.0%