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+--- Thread: How to expand (x-1.95)(x-4)(x+7.98) in the Prime? (/thread-6131.html)
How to expand (x-1.95)(x-4)(x+7.98) in the Prime? - bigjohnson - 04-24-2016 03:42 PM
Hey guys, I'm having a problem expanding expressions involving decimal numbers.
I type the expression (in CAS) then I put to simplify, but it doesn't. It returns the same expression, but if I do with natural numbers it does expand.
For example, for (x-1.95)(x-4)(x+7.98) it should return x^3+2.03 x^2-39.681 x+62.244, but it doesn't, it returns the same input expression.
But for example, if I type (x-1)(x-4)(x+7) and put to simlify, it does return the expanded form x^3+2 x^2-31 x+28
Does anyone know how to overcome this?
Thanks a lot!
RE: How to expand (x-1.95)(x-4)(x+7.98) in the Prime? - roadrunner - 04-24-2016 03:56 PM
Try:
normal((x-1.95)*(x-4)*(x+7.98)) --> x^3+2.03*x^2-39.681*x+62.244
normal((x-1)*(x-4)*(x+7)) --> x^3+2*x^2-31*x+28
-road
RE: How to expand (x-1.95)(x-4)(x+7.98) in the Prime? - DrD - 04-24-2016 03:58 PM
Did you try:
expand((x-1.95)*(x-4)*(x+7.98)) ==> x^3+2.03*x^2-39.681*x+62.244
expand((x-1)*(x-4)*(x+7)) ==> x^3+2*x^2-31*x+28
-Dale-
RE: How to expand (x-1.95)(x-4)(x+7.98) in the Prime? - Terje Vallestad - 04-24-2016 04:00 PM
(04-24-2016 03:42 PM)bigjohnson Wrote: Hey guys, I'm having a problem expanding expressions involving decimal numbers.
I type the expression (in CAS) then I put to simplify, but it doesn't. It returns the same expression, but if I do with natural numbers it does expand.
For example, for (x-1.95)(x-4)(x+7.98) it should return x^3+2.03 x^2-39.681 x+62.244, but it doesn't, it returns the same input expression.
But for example, if I type (x-1)(x-4)(x+7) and put to simlify, it does return the expanded form x^3+2 x^2-31 x+28
Does anyone know how to overcome this?
Thanks a lot!
If you use expand() as per your subject line you get the result you want.
I.e. expand((x-1.95)*(x-4)*(x+7.98)) -> x^3+2.03 x^2-39.681 x+62.244
Cheers, Terje