{G #/1.2º Displays current equation.

{œH

#@value

Solves for H; prompts for V.

7500 f

/)

Stores 7500 in V; solves for H.

Now check the quality of this solution — that is, whether it returned an exact root — by looking at the value of the previous estimate of the root (in the Y–register) and the value of the equation at the root (in the Z–register).

Keys: Display:Description:

9

)

This value from the Y–register is the

 

 

estimate made just prior to the final

 

 

result. Since it is the same as the

 

 

solution, the solution is an exact root.

9

)

This value from the Z–register shows

 

 

the equation equals zero at the root.

The dimensions of the desired box are 50 10 15 cm. If you ignored the upper limit on the height (20 cm) and used initial estimates of 30 and 40 cm, you would obtain a height of 42.0256 cm — a root that is physically meaningless. If you used small initial estimates such as 0 and 10 cm, you would obtain a height of 2.9774 cm — producing an undesirably short, flat box.

If you don't know what guesses to use, you can use a graph to help the behavior of the equation. Evaluate your equation for several values of the unknown. For each point on the graph, display the equation and press W— at the prompt for x enter the x–coordinate,and then obtain the corresponding value of the equation, the y–coordinate.For the problem above, you would always set V = 7500 and vary the value of H to produce different values for the equation. Remember that the value for this equation is the difference between the left and right sides of the equation. The plot of the value of this equation looks like this.

7–10 Solving Equations

File name 32sii-Manual-E-0424

 

Printed Date : 2003/4/24

Size : 17.7 x 25.2 cm