Finding Values of X

[Jeffrey]

Good day,

im just a newbie in VBA, i wonder if we can find X using VBA codes to
satisfy the equation below.

X^2 -28X+16 = 0.

Basically i want to find the value of X so that the left side of the
equation is equal to zero.

Thanks in advance.

 

[RB Smissaert]

In Cell C1 put this formula:
= A1* (28-A1)

Load Solver by doing Tools, Add-ins and tick the Solver add-in.

Then Tools, Solver and

Set Target Cell C1
Equal to value of -16
By changing value of A1
Press Solve

To put it all in VBA do the same as above while recording a macro and study
the recorded code.


RBS

 

[Gary''s Student]

Nearly the same as the equivalent worksheet formulas:

=(28+(28^2-4*16)^0.5)/2
=(28-(28^2-4*16)^0.5)/2

which yield:

27.41640786
0.583592135

 

[JLGWhiz]

Or you can use the Quadratic theory:

Sub uo()
x = -(-28) + Sqr((-28) ^ 2) - (4 * 1 * 16) / (2 * 1)
MsgBox x
x = -(-28) - Sqr((-28) ^ 2) - (4 * 1 * 16) / (2 * 1)
MsgBox x
End Sub

 

[JLGWhiz]

Works better with all the parentheses in:

Sub uo()
x = -(-28) + Sqr(((-28) ^ 2) - (4 * 1 * 16)) / (2 * 1)
MsgBox x
x = -(-28) - Sqr(((-28) ^ 2) - (4 * 1 * 16)) / (2 * 1)
MsgBox x
End Sub

 

[Jeffrey]

Good day,

Hi guys, thanks much for your response. they work. but have to
rephrase my question.
i should have ask this one at the first place.


r = W^2 + 4(H^2)
----------------------
8H

Values given are "r" and "W". And im looking for H.
I would like the user to enter the value of r and W in say a1 and a2
respectively, and the value of
H will be given.

Please advice. Thanks in advance.

 

[Rick Rothstein \(MVP - VB\)]

Yes, asking the question you actually want answered would seem to make more
sense. Anyway, solving for H yields these two equations.....

H1: =R1+SQRT(R1*R1-W1*W1/4)

H2: =R1-SQRT(R1*R1-W1*W1/4)

Where I picked cells who column address matched your variable letters.

Rick

Good day,

Hi guys, thanks much for your response. they work. but have to
rephrase my question.
i should have ask this one at the first place.


r = W^2 + 4(H^2)
----------------------
8H

Values given are "r" and "W". And im looking for H.
I would like the user to enter the value of r and W in say a1 and a2
respectively, and the value of
H will be given.

Please advice. Thanks in advance.

 

[Jeffrey]

Thanks a lot mate. This is such a relief.

Wish everyone a fantastic weekend.

 

[RB Smissaert]

OK, I thought that you had worked out that the value couldn't simply be
simply calculated.
As you can no need for Solver. Still, it may come in handy one day.

RBS