Question about Casio fx-115MS

Robert Monsen wrote in news:UDwqd.411559$wV.308600@attbi_s54:

Did this twice and both times with A= on the first line, the second line was 0.

Thus, for a value of B=10k, a value of A=2.05k will

Tried a really simple equation, 3 = A*B (3 Alpha = Alpha A * Alpha B), with B=3. Again, with A= showing on first line, second line showed 0.

Jack

Solve uses an iterative solver to try to figure out a numerical solution. Say you want to figure out the right resistor value to make divider, but you were too lazy to do the algebra in your head. If your input voltage was 10 volts, and you wanted 1.7 volts out, you could type

You then get a prompt for A, as in "A? ". Say you want to solve for A. Then, hit the down key (the bottom of the circular key). You get a "B?" prompt. Enter a value for B. (say you have a 10k resistor)

then get back to the A? prompt by typing up arrow (the top of the circular key) and type

shift solve

it'll crank for a bit, then display A= on the first line, and 2.048...k on the second line. Thus, for a value of B=10k, a value of A=2.05k will get you 1.7V.

The trick is to use the up and down key to enter values for variables you have values for, and then use shift solve on the one you want the value for.

Robert Monsen wrote in news:e7Pqd.175760 $R05.45470@attbi_s53:

Am I wrong to expect the calculator to solve "3=A*B" for A, given B = 3? I believe I did exactly what you said to do. I'll spell out completely the keys I pushed : 3, ALPHA, =, ALPHA, A, *, ALPHA, B, SHIFT, SOLVE, down-arrow, 3, =, up-arrow, SHIFT, SOLVE. At this point the top line shows A=; the bottom line shows 0. (by * I mean the multiplication key, "X").

Thanks for being so patient with me.

Jack

Robert Monsen wrote in news:4vSqd.168278$HA.118072 @attbi_s01:

Yes, I've been in comp mode.

Jack

Again, you switch to B using the 'down' key, which is the bottom of the circular key. Enter the values for the unknowns you want, and then select the one you want to solve for. enter 'shift solve' and it will solve the equation if it can do it using iteration.

No, it works for me.

Make sure you are in 'comp' mode, not 'cmplx' mode. The solve function does not work in complex mode. Enter 'mode clr' and then '1' to enter 'comp' mode.

After entering your formula for 3=A*B, can you switch between "A=" and "B=" on the top display line using up and down arrow?

Robert Monsen wrote in news:3GWqd.169549$HA.22176 @attbi_s01:

No. After "A=" appears, up-arrow produces "3", and I'm stuck there. Down-arrow doesn't work after "A=" appears.

Jack

Robert Monsen wrote in news:Jfcrd.695662$8_6.282472@attbi_s04:

Yes, that's what I'm pushing.

Thanks,

Jack

Look at the calculator. There is a big round button right underneath the center of the display. The up and down buttons are on the top and bottom of that. Is that what you are pushing? If not, then that's your problem. If so, then your calculator is broken.