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jahid89

Junior Member
what is the limit of y when y-> -3+ (y^5 - y^3)/((y^2) -9)?
when y tends to -3 by the right....

Lim x→-3+ [ (x^5 - x^3) / (x^2 -9) ] = Lim x→-3+ [ f(x)/g(x) ]

L'Hospital is not needed since f(-3) = ∞, g(-3) = 0
So we directly conclude
Lim x→-3+ [ f(x)/g(x) ] = ∞ =undefined :SMILY139:
 

jahid89

Junior Member
next question.....

what is the domain of f(z)=3/4-z^2+log(base)10(z^3-z)?

i.e
f(z)=(3/4)-z^2+log(base)10(z^(3)-z)
 

arzafar

Junior Member
next question.....

what is the domain of f(z)=3/4-z^2+log(base)10(z^3-z)?

o yaar halka hoja. :SMILY139:
i mean dont use so many symbols because we cant use mathematical notation and this can lead to confusion. your previous question also wasnt entirely clear.

for eg. z^3-z could mean z raised to the power 3 and then minus z
or it could also mean z raised to the power 3-z.
 

jahid89

Junior Member
o yaar halka hoja. :SMILY139:
i mean dont use so many symbols because we cant use mathematical notation and this can lead to confusion. your previous question also wasnt entirely clear.

for eg. z^3-z could mean z raised to the power 3 and then minus z
or it could also mean z raised to the power 3-z.

oops ...cool down.... samjh gya yaar
my question is..

find domain... f(z)=(3/4)-z^2+log(base)10(z^(3)-z)
 

arzafar

Junior Member
oops ...cool down.... samjh gya yaar
my question is..

find domain... f(z)=(3/4)-z^2+log(base)10(z^(3)-z)

lemme give this one a try

f(z) = X + Y
where X = (3/4)-z^2 and Y = lg[z^3 - z]

domian (X) = {a: a is real}

Y = lg[z(z^2 - 1)] = lg [z(z-1)(z+1)]
domain (Y) = {a: a>0 and a is not= 1}

domian f(z) = domain (X) n domain (Y) {n - intersection}
domain f(z) = {a: a>0 and a is not= 1}
 

jahid89

Junior Member
lemme give this one a try

f(z) = X + Y
where X = (3/4)-z^2 and Y = lg[z^3 - z]

domian (X) = {a: a is real}

Y = lg[z(z^2 - 1)] = lg [z(z-1)(z+1)]
domain (Y) = {a: a>0 and a is not= 1}

domian f(z) = domain (X) n domain (Y) {n - intersection}
domain f(z) = {a: a>0 and a is not= 1}

hummmmmm :eek:... m not satisfy with ur answer :SMILY286:
domain is not define properly...:SMILY259:
 

jahid89

Junior Member
next question.....

what is the domain of f(z)=3/4-z^2+log(base)10(z^3-z)?

i.e
f(z)=(3/4)-z^2+log(base)10(z^(3)-z)

consider the equetion....
when z^3 - z < = 0 the f( z ) would be meaning less and undefined log(0)

z^3 - z ! = 0 and

=> z ( z^2 - 1 ) ! = 0

=> z ( z + 1 ) ( z - 1 ) ! = 0

=> z ! = 0 and z + 1 ! = 0 and z -1 ! = 0

=> z ! = 0 and z ! = -1 and z ! = 1

and z^3 - z > 0

=> z ( z^2 - 1 ) > 0

=> z > 0 and z > 1 and z > -1 = > z should be greater than -1

so domain of f ( z ) is ( -1 , 0 ) u ( 1 , 2 ] u [ 2 , ∞ )
:SMILY139::SMILY139:
 

arzafar

Junior Member
consider the equetion....
when z^3 - z < = 0 the f( z ) would be meaning less and undefined log(0)

z^3 - z ! = 0 and

=> z ( z^2 - 1 ) ! = 0

=> z ( z + 1 ) ( z - 1 ) ! = 0

=> z ! = 0 and z + 1 ! = 0 and z -1 ! = 0

=> z ! = 0 and z ! = -1 and z ! = 1

and z^3 - z > 0

=> z ( z^2 - 1 ) > 0

=> z > 0 and z > 1 and z > -1 = > z should be greater than -1

so domain of f ( z ) is ( -1 , 0 ) u ( 1 , 2 ] u [ 2 , ∞ )
:SMILY139::SMILY139:

oh man well i basically messed up the final answer
 

jahid89

Junior Member
next proble,....
Now comes the difficult part
y=? does the graph of f (y) have a horizontal tangent? f (y) = 3 (y^3) + 7 (y^2) + 3 (y) + 6
 

arzafar

Junior Member
next proble,....
Now comes the difficult part
y=? does the graph of f (y) have a horizontal tangent? f (y) = 3 (y^3) + 7 (y^2) + 3 (y) + 6

is "y=?" a question? anyways

differentiate f(y) wrt y
f'(y) = 9y^2 +14y + 3

at the horizontal tangent f '(y) = 0
=> 9y^2 + 14y + 3 = 0
=> y^2 + (14/9)y + 1/3 = 0
=> (y + 7/9)^2 - (7/9)^2 + 1/3 = 0
=> (y+ 7/9)^2 = 49/81 - 27/81
=> (y+ 7/9)^2 = 22/81
=> y = -7/9 +/-(22/81)^(1/2)
 

jahid89

Junior Member
is "y=?" a question? anyways

differentiate f(y) wrt y
f'(y) = 9y^2 +14y + 3

at the horizontal tangent f '(y) = 0
=> 9y^2 + 14y + 3 = 0
=> y^2 + (14/9)y + 1/3 = 0
=> (y + 7/9)^2 - (7/9)^2 + 1/3 = 0
=> (y+ 7/9)^2 = 49/81 - 27/81
=> (y+ 7/9)^2 = 22/81
=> y = -7/9 +/-(22/81)^(1/2)

y = -7/9 +/-(22/81)^(1/2)= -1.298935084
correct..
good brother:jumpclap::wavyarms:
 

arzafar

Junior Member
you have 64 blue chips. While waiting in line at the casino to cash them in you decide to bet half that number on the toss of a coin. Win or lose, you bet half of your new total on a second toss; then half of the new total on a third toss; and so on, until you reach the cashier's window. Say you make 6 tosses in all, winning three and losing three. Do you come out even, ahead or behind and in case you come out ahead or behind by what amount?
 

arzafar

Junior Member
you lose 37 chips. It doesn't matter in what order you win or lose as long as you win 3 and lose 3 bets.

for eg.

1) bet 32; lose 32 ; total = 32 + 0 = 32
2) bet 16; win 32 ; total = 16 + 32 = 48
3) bet 24; lose 24; total = 24 + 0 = 24
4) bet 12; win 24; total = 12 + 24 = 36
5) bet 18; win 36; total = 18 + 36 = 54
6) bet 27; lose 27; total = 27 + 0 = 27

money lost = 64 - 27 = 37
 

jahid89

Junior Member
you lose 37 chips. It doesn't matter in what order you win or lose as long as you win 3 and lose 3 bets.

for eg.

1) bet 32; lose 32 ; total = 32 + 0 = 32
2) bet 16; win 32 ; total = 16 + 32 = 48
3) bet 24; lose 24; total = 24 + 0 = 24
4) bet 12; win 24; total = 12 + 24 = 36
5) bet 18; win 36; total = 18 + 36 = 54
6) bet 27; lose 27; total = 27 + 0 = 27

money lost = 64 - 27 = 37

oops :shymuslima1: littile bit mistake
 
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