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Solving equations with the CASIO FX-991ES calculator

I have a query to whether the Casio 991ES calculator (the silver one) can actually solve simple equations, such as

2x+5=11

or even harder, quadratic equations?

Please help

Reply 1

Magnum Opus

is it graphics? draw a graph with the equation..?

Surely you can solve 2x+5=11 in your head?

Yes it does.

c|2iMiNaL

Yes it does.

How do you set it up so that it does, I need some help please

Reply 4

alex_hk90

(KateekaK)²

I have a query to whether the Casio 991ES calculator (the silver one) can actually solve simple equations, such as

2x+5=11

or even harder, quadratic equations?

Yes, it can. If the equation is in one of the supported forms, you can just do (MODE, 5: EQN) and then choose one of the 4 options. In this mode it will give you all the solutions to the equation. If it's not a supported form, it can do it numerically if you type the equation in COMP mode and then do (SHIFT+CALC [SOLVE]), but this will only give you one solution if I remember correctly.

Reply 5

thelostchild

I think it uses some sort of Newton Raphson process to solve the equation so it will only find one root at a time

you enter the equation in the normal mode using Alpha then Calc for the equals sign and alpha then ) for the X

then press shift then solve, it should now say solve for X and some number, enter your first best guess for the solution now then press equals and it should give you the solution :smile:

For equations with multiple solutions it will come up with only one depending on the guess you give it :smile:

Reply 6

c|2iMiNaL

(KateekaK)²

How do you set it up so that it does, I need some help please

Using your initial example: 2x+5=11

Enter the left hand side of the equation, so 2X+5 and then select ALPHA > CALC.

Now enter the right hand side of the equation and then select SHIFT > CALC > = (Equals).

Reply 7

jamesair99

yeah you just use the solve like that

but you can also go mode >> eqn

and then solve cubic equations (it tells you the 3 values for x)
and it can also solve 3 lots of simulatenous equations (very useful for vectors)