Find when 2x^3+x-5 is equal to zero

  • Thread starter Thread starter UrbanXrisis
  • Start date Start date
  • Tags Tags
    Zero
AI Thread Summary
To find when 2x^3 + x - 5 equals zero, the equation can be analyzed using the Rational Root Theorem, which suggests there are no rational solutions. This indicates that the polynomial cannot be factored using integer coefficients. While a cubic formula exists, it is complex and unwieldy. A practical approach is to solve the equation numerically or graphically, as suggested by one participant who used a graphing calculator to identify the x-intercept. Therefore, numerical methods or graphing are recommended for finding the roots of this polynomial.
UrbanXrisis
Messages
1,192
Reaction score
1
I need to find when 2x^3+x-5 is equal to zero and I'm stuck

2x^3+x-5=0
5=2x^3+x...then what?
 
Physics news on Phys.org
You sure you have the right problem?


There is a really nice theorem for finding all of the rational zeroes of a polynomial that involves the first and last terms of the polynomial, have you seen it yet?
 
Hurkyls method show that there are no rational solutions. That means that this cannot be factored with integer coefficients. There is a "cubic formula" but it is very messy. It is probably best solved numerically.

(The method I used was to graph it on my calculator, then "zoom" in on the x-intercept!)
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Momentum: why don't the two carts become one?
Replies
32
Views
1K
If the wave function is normalized, what is the probability density at x?
Replies
4
Views
2K
Conservation of momentum (center of mass) in projectile launches
Replies
15
Views
1K
Why is the result different in Method 2 for the rotating rod experiment?
Replies
11
Views
2K
Solve ##\dfrac{3x-6}{5-x}+\dfrac{11-2x}{10-4x}=3\dfrac{1}{2}##
Replies
3
Views
2K
Elastic Potential Energy - Positive or Negative?
Replies
5
Views
1K
Vertical spring & maximum length
Replies
6
Views
1K
Calculate velocities in COM reference frame for 2D collision
Replies
27
Views
1K
Calculating Time with Forces Acting on a Block
Replies
5
Views
1K
Resistance force changing the velocity of an object
Replies
8
Views
1K

Hot Threads

Recent Insights

Back
Top