HP -11C Owner's Handbook Manual page 76

148 Section 10: Applications Programs
The three loop equations are:
Loop 1 41, — 41 + 151, —151,—40=0
Loop 2 41 —41, + 8ly + 10In— 101, =0
Loop 3 10Ig — 101) + 115 + 151g — 155, =0
or in matrix form
19-4 -15) [7 40
-4 22 -10]]%]=| 0
"15 -10 26] | 5 0
Keystrokes
19 (STO]5
4 (cHs)[STO}6
15 [CHS)[STO}]7
4 (cHs)(ST0}8
9
STO]CJO
(sto)C)
[sto]C}
26 [sTo}f-]3
Delete the simultaneous equations routine if it is still in program
memory, and insert the determinant routine.
A 2,402.0000
Delete the determinant routine and insert the simultaneous
equations routine.
Display
n=
40 [ENTER
O (ENTER) (C 7.8601
{RS} 4.2298
R/S 6.1615
Yow
Fa ee
Section 10: Applications Programs 149
Systems of Linear Equations
With Three Unknowns
Equations: A system of linear equations can be expressed as
AX =B.
ayy M2 413
For three unknowns, A=] ag ag ag3
431 432 433
x1 by
X= | xe B= | by
x3 bs
det A = ay 1(ag2dgg ~ 423432) ~ 212421433 ~ 423491)
+ ay9(421 432 ~ @22491) «
x;'s are solved by
det (i)
x=
Det A