How Are Solutions -91.9 and 170 Derived Using the Quadratic Formula?

AI Thread Summary
The discussion centers on the evaluation of the quadratic formula, specifically the expression -1 +/- √11.24 / -0.0256, which yields the solutions -91.9 and 170. The original poster was confused about how these values were derived and sought clarification. Participants advised evaluating the two expressions separately and emphasized the importance of using proper parentheses in calculations. The poster realized their mistake in handling the fraction and thanked the contributors for their guidance. Accurate evaluation of the quadratic formula is crucial for obtaining the correct solutions.
Kimosabae
Messages
6
Reaction score
0
Could someone please help with this evaluation?

Homework Statement



-1+/-√11.24/-0.0256

The solutions given for this are -91.9 and 170 and I am truly flabbergasted as to how this instructor achieved these values.
 
Physics news on Phys.org
The way you have written the quadratic formula may be confusing you.

Try evaluating (-1 + SQRT (11.24))/(-0.0256) and (-1 - SQRT (11.24))/(-0.0256) separately.

If you don't get -91.9 and 170 respectively, your calculator is broken or you are doing something wrong punching in the numbers.
 
  • Like
Likes 1 person
And don't forget the proper parenthesis.
\frac{\left(-1 \ \pm \sqrt{11.24} \ \right)}{-0.0256}
 
  • Like
Likes 1 person
Thanks so much, gentlemen. I was evaluating incorrectly. I was trying to put -0.0256 over 1 to get rid of the fraction, multiply by the -1 and then add +0.0256 to +/-√11.24 giving me the incorrect values. Thanks again!
 
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}...
Back
Top