dprinz99:

tanks bro,datx a grt job.ah reali appreciate.
going tru dis problm,ah c DAT we sum pple r witch in mathz,(u inclusiv)
I solved to a certain point but didn't knw wen to apply d quad formula.

Madmathecian:
The height h in feet of a model rocket above the ground t seconds after lift-off is given by
h(t) = −5t² + 100t, if 0 ≤ t ≤ 20

And 0, if t > 20


1. Find and interpret h(10) and h(60).


2. Solve h(t) = 375 and interpret your answers.

ladokuntlad:

1)
h(10)=-5(10)²+100(10)
=-5(100)+1000
=500
implies that at t=10(tenth seconds), the rocket is 500feet in the air.
h(60)=0
because wen we insert dat into d equation we get a negative result.
and its not posible for a height to neative. dat implies dat at t=60 the rocket is already back to the ground and its at rest hence height is zero(0)

2)h(t)=375
implies
375=-5(t)²+100(t)
dividing tru by 5 givs
75=-t²+20t
making t² positive by taking all values from the RHS to the LHS, we have
t²-20t+75=0
by factorization we av
t²-5t-15t+75=0
t(t-5)-15(t-5)=0
(t-5)(t-15)=0
thus t=5 or t=15
implies that
at the 5th seconds(t=5) the rocket was taking off(moving upward)
while at the 15th seconds(t=15) the rocket was already on its way back to the ground.
(not good at physics(always d C candidate) so pardon my poor interpretation)

ladokuntlad:

1)
h(10)=-5(10)²+100(10)
=-5(100)+1000
=500
implies that at t=10(tenth seconds), the rocket is 500feet in the air.
h(60)=0
because wen we insert dat into d equation we get a negative result.
and its not posible for a height to neative. dat implies dat at t=60 the rocket is already back to the ground and its at rest hence height is zero(0)

2)h(t)=375
implies
375=-5(t)²+100(t)
dividing tru by 5 givs
75=-t²+20t
making t² positive by taking all values from the RHS to the LHS, we have
t²-20t+75=0
by factorization we av
t²-5t-15t+75=0
t(t-5)-15(t-5)=0
(t-5)(t-15)=0
thus t=5 or t=15
implies that
at the 5th seconds(t=5) the rocket was taking off(moving upward)
while at the 15th seconds(t=15) the rocket was already on its way back to the ground.
(not good at physics(always d C candidate) so pardon my poor interpretation)

stlaibrowne:

Good job though but I don't totally agree with the h (60) interpretation because at t =60 the height is negative doesn't necessarily means the rocket is back to ground level it might as well means the time function is not valid for state or height of rocket at t=60

ladokuntlad:


am 10000000000000000% sure the rocket is back to d ground
dats y h=0 at that point

stlaibrowne:


I am 100000000000000% sure you need to read the question again. Because actually at t=60 h is not zero but h=-12000 and that's not zero. Get my point ?

naturalwaves:
@ Ladokuntlad, it is possible for height to be negative in physics particularly when an object is going up or down. If you get a negative height, it means the object is going against gavity( I.e moving up).

ladokuntlad:

i strongly disagree as pertaining to this particular question above.
Why?
since some certain condition as been given so its already under a constraint, which cant make us say its going against gravity (-g) even at -g(going against gravity) we don't get our distance to b negative.
I stand to b corrected though.
Bt for dis particular question above.
d reason i gave is still very legit until someone comes here and give His/Her own clear reason

ladokuntlad:

well in pure mathematics and some other mathematical methods question
we have something called boundary value problems(BVP) wich involves aving some constraints/conditions on a question.
Well i wont go further dan dat.

let the referees in the house come and second ur opinion or mine

Madmathecian:

Find and simplify the diference quotients for the following functions

1. f(x) = x² − x − 2

2. g(x) = 3/( 2x + 1)

stlaibrowne:

Good job though but I don't totally agree with the h (60) interpretation because at t =60 the height is negative doesn't necessarily means the rocket is back to ground level it might as well means the time function is not valid for state or height of rocket at t=60

stlaibrowne:


I am 100000000000000% sure you need to read the question again. Because actually at t=60 h is not zero but h=-12000 and that's not zero. Get my point ?

masperano:


I think you should be the one to read the question. Ladokuntlad is very correct. The height function is a parabola. It was also stated in the question that h(t)=0 when t>20. my question to you is, is 60 greater than 20? if yes please apologize to Ladokuntlad (lol). It is worth adding that at t=0 and 20 the height is zero.(this implies it goes up reaches its maximum at t=10 before coming down) the function is also symmetric. Pls try to read questions and understand the interpretation before solving. Cheers

Madmathecian:



Not that I don't understand you but you should read what ladokuntlad wrote above succinctly, they ar constraints in exponential modelling.
H(60) is zero because of the strict inequality in the problem above.

masperano:

I think you should be the one to read the question. Ladokuntlad is very correct. The height function is a parabola. It was also stated in the question that h(t)=0 when t>20. my question to you is, is 60 greater than 20? if yes please apologize to Ladokuntlad (lol). It is worth adding that at t=0 and 20 the height is zero.(this implies it goes up reaches its maximum at t=10 before coming down) the function is also symmetric. Pls try to read questions and understand the interpretation before solving. Cheers

ladokuntlad:

1)
h(10)=-5(10)²+100(10)
=-5(100)+1000
=500
implies that at t=10(tenth seconds), the rocket is 500feet in the air.
h(60)=0
because wen we insert dat into d equation we get a negative result.
and its not posible for a height to neative. dat implies dat at t=60 the rocket is already back to the ground and its at rest hence height is zero(0)
[/b]

stlaibrowne:

Good job though but I don't totally agree with the h (60) interpretation because at t =60 the height is negative doesn't necessarily means the rocket is back to ground level it might as well means the time function is not valid for state or height of rocket at t=60

Laplacian:

ur interpretation is right sir...nice criticism!!!

masperano:
So I have a joke great mathematicians(told by my pde lecturer(he is Russian)).

A team of Engineers from England visited Germany and they saw a black goat. They came back and said "all goats are black in Germany"

Next a team of Physicist visited Germany and they saw a black goat.They came back and said "there is one black goat in Germany".

Finally a team of Mathematicians visited Germany and saw a black goat. They came back and said. "There exist at least one black goat in Germany which is black".

Moral of the story always check the rightness of your statement as a scientist.

Cheers my people

MathsChic:

Only a mathematician can tell such joke, cos it's all in favour of mathematicians. Funny, clever joke


Today I was thinking something. The ratio of the circumference of a circle to its diameter is a number that doesn't occur in nature any other way, besides as a ratio of circumference to diameter. Isn't that just spectacular? Or am I wrong? Does it have other occurences?

iameugene:
Join our jamb whatsapp group num: 07019747550

LordPherule:
Since I've been studying Mathematics, I just realised there is cramming in Mathematics in my 3rd year. It suck!

saipn:
Gurus help me solve dis set question
1)A company employs 100 people,65 of whom are men. 60 people,including all the women,are paid weekly.How many of the men are paid weekly?
2)In a village all the people speak hausa or English or both.97% speak hausa and 64% speak English,what percentage speak both languages?
3)In a survey of villagers,it is found that 20% of the people have visited kano and 25%have visited portharcourt. If 5% have been to both cities,what percentage have visited neither place?