calculate value

[merlin_the_magician]

Very confusing problem….

I need to calculate many values, using a formula like the one beneath, in which "d" is unknown. How can i have excel calculate d?

(1,89d²) - (4,92d) - 9,84 = 0

d should have TWO possible values:
d = -1,33
d = +3,93

 

[Iridium]

Hoi mijn vriend!

You trying to solve a quadratic? If so PM me your e-mail as I think I have a workbook that may be useful to you

HTH

 

[GorD]

I tried to reproduce this using solver. I did thai by setting the formula in a cell and replacing your "d" with a cell reference. You then set the target value for the cell with the formulato 0 and add any constraints. I had to do this twice, to get the two values, once specifying that change cell must be >0.

The results it reurned were@

-formula result: 9.58862E-07 D= -1.325288828


-formula result: 5.38735E-07 D= 3.928463582

Don't no if this helps, or of its accurate enough

 

[Iridium]

Quadratics.xls
	A	B	C	D	E	F	G	H
1	Equationtosolvequadratics
2	Entera,bandcintheblueboxes				a	b	c
3	Where				4	3	-1
4
5
6
7
8					x=	0.25	or	-1.00
Sheet1

Where ax²+bx+c=0, x=-b±SQRT(b²-4ac/2a)

HTH

 

[Seti]

Iridium just beat me, but here is the solution using your actual values in a much less user friendlylayout:

Book1
	B	C	D	E
3	a	1.89
4	b	-4.92
5	c	-9.84
6
7		3.928464
8		-1.32529
Sheet1

 

[merlin_the_magician]

I asked Iridium to PM the template to me, so that would be of rather good use. I'm very glad this can be done by excel, because calculation by hand is much work and very hard as well because of the complicated values.

By the way, what about the formula that is used?
Mathematic rule: (a+b)² = a² + 2ab + b² The formula does someting i do not quite understand...



Thank you for your efforts as well seti. I knew it couldn''t be that hard to solve...