Microsoft Office Tutorials and References
In Depth Information
Solving Simultaneous Equations
Calculating the volume of a pyramid
Calculate the area of the base, multiply by the height, and then divide by 3. This formula
calculates the volume of a pyramid. It assumes cells named width (the width of the base), length (the
length of the base), and height (the height of the pyramid).
Solving Simultaneous Equations
This section describes how to use formulas to solve simultaneous linear equations. The following
is an example of a set of simultaneous linear equations:
3x + 4y = 8
4x + 8y = 1
Solving a set of simultaneous equations involves finding the values for x and y that satisfy both
equations. For this set of equations, the solution is as follows:
x = 7.5
y = –3.625
The number of variables in the set of equations must be equal to the number of equations. The
preceding example uses two equations with two variables. Three equations are required to solve
for three variables (x, y, and z).
The general steps for solving a set of simultaneous equations follow. See Figure 10-3, which uses
the equations presented at the beginning of this section.
1. Express the equations in standard form. If necessary, use simple algebra to rewrite the
equations such that the variables all appear on the left side of the equal sign. The two
equations that follow are identical, but the second one is in standard form:
3x –8 = –4y
3x + 4y = 8
2. Place the coefficients in an n x n range of cells, where n represents the number of
equations. In Figure 10-3, the coefficients are in the range I2:J3.
3. Place the constants (the numbers on the right side of the equal sign) in a vertical range
of cells. In Figure 10-3, the constants are in the range L2:L3.
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