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The graph of y=ax^(2)+bx+c is given as shown. Which of the following is / are true?
I. a<0
II. b<0
III. c<0
A. I only
B. I and II only
C. I and III only
D. II and III only
E. I, II and III
 one year ago
 one year ago
The graph of y=ax^(2)+bx+c is given as shown. Which of the following is / are true? I. a<0 II. b<0 III. c<0 A. I only B. I and II only C. I and III only D. II and III only E. I, II and III
 one year ago
 one year ago

This Question is Closed

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352549825053:dw
 one year ago

Kira_YamatoBest ResponseYou've already chosen the best response.0
(C) c < 0 as graph cuts yaxis below the xaxis a < 0 because graph is frowning curve
 one year ago

hashsam1Best ResponseYou've already chosen the best response.1
E) inverted U shape meaning a<0 intersecting y axis at negative means C is less than 0 c<0 and also there is shift along x axis in right direction means b<0
 one year ago

Kira_YamatoBest ResponseYou've already chosen the best response.0
Overlooked the detail for b<0... Sorry
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
I am confusing why b>0 is correct
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
the line of symmetry x = b/2a, is a positive value, and we know a < 0 so b > 0
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
I am sorry that I type it wrongly. It should be : "I am confusing why b<0 is correct"
 one year ago

03225186213Best ResponseYou've already chosen the best response.0
a<0 because parabola opens downward
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
I know a<0 and c<0, I just don't know why b<0 is correct
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
so the answer is C?
 one year ago

hashsam1Best ResponseYou've already chosen the best response.1
dw:1352551798883:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
@hashsam1 the line of symmetry is the line x = b/2a. according to the graph it is to the right of the yaxis (so the sign of b/2a is positive). we know that a < 0, so if b < 0 then the sign of b/2a is ()/2() is negative.
 one year ago

phiBest ResponseYou've already chosen the best response.0
a simple example with 2 positive roots x=1 and x=2 the polynomial would be (x1)(x2) = x^2 +3x 2 this suggests a<0 b>0 c<0
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
I understand now, thank you so much :)
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
another question If f(x)=x(1/x), then f(x)f(1/x)= ?
 one year ago

hashsam1Best ResponseYou've already chosen the best response.1
oops yes right i over looked the equation thinking its just a normal quadratic equation.
 one year ago

phiBest ResponseYou've already chosen the best response.0
If f(x)=x(1/x), then f(x)f(1/x)= ? replace f(x) with x 1/x replace f(1/x) with 1/x  x
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352552240065:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352552332194:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352552484497:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
1/(1/x) = x. try again.
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
oh .dw:1352552602486:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
you still need to combine x + x
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352552793347:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
i'll accept either form.
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
another question If f(x)=10^(2x), then f(4y)=?
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
A. 10^(4y). B. 10^(2+4y) C. 10^(8y) D. 40^(y) E. 40^(2y)
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
replace x by 4y, what do you get?
 one year ago

nubeerBest ResponseYou've already chosen the best response.0
f(x)=10^(2x) f(x)=10^(2(4y))
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
If f(x)=x/(1x), then f(1/x)f(x)=?
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352553510302:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
\[\huge f(x) = \frac{ (x) }{ 1(x) }\]
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
If f(x)=x/(1x), then f(1/x)f(x)= f(1/x) = (1/x)/(1(1/x)) = 1/x((x1)/x) f(x) =(x)/(1(x)) = x/(1+x) f(1/x)f(x) = 1/x((x1)/x) times x/(1+x) f(1/x)f(x) = x/(x((x1)/x)(1+x))
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
o.o errrr.... wait a moment
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
f(1/x)f(x) = x/(x((x1)/x)(1+x)) f(1/x)f(x) = x/((x1)(x+1))
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554094668:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554171343:dw
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
dw:1352554144569:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
is it necessary for you to give me a big cross....... I got it :)
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554351232:dw
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
dw:1352554433711:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554512663:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554601402:dw
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
dw:1352554549107:dw
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
dw:1352554682501:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
we're not discussing' we're exchanging notes. hahaha
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554679681:dw
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
dw:1352554776614:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352554942585:dw
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
what's the answer to your problem \[\huge f(\frac{ 1 }{ x })f(x)\]
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
A. 1/2 B. 1 C. (1x)/(1+x) D. x/(1x^(2)) E. x/(x^(2)1) no answer since this is past paper, my teacher haven't give us the answers yet
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
I still cannot get the answer
 one year ago

CallistoBest ResponseYou've already chosen the best response.1
Please start a new post for a new question. If possible, please also put them in the right categories (subtopics). Thanks!
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
\[\large f(1/x)f(x) = \frac{ 1/x }{ 11/x }\frac{ (x) }{ 1(x) }\] \[\large = \frac{ 1 }{ 1+x \frac{ 1 }{ x }1 } \times \frac{ x }{ x }\]
 one year ago

sirm3dBest ResponseYou've already chosen the best response.2
just carry out the multiplication and you'll get (D)
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
dw:1352556469608:dw I get this only...
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
f(1/x)f(x) = x/(x((x1)/x)(1+x)) f(1/x)f(x) = x/((x1)(x+1)) f(1/x)f(x) = x/(x^2 1) f(1/x)f(x) = x/(x^2 +1) f(1/x)f(x) = x/(1x^2) the answer is D x/(1x^2)
 one year ago

gerryliyanaBest ResponseYou've already chosen the best response.0
you got it @kryton1212 ???? take it a simply way..,hehe
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
confusing................. I think it later another question If a,b and c are all positive, which of the following may represent the graph of ax+by+c=0?dw:1352556954406:dw
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
@hartnn would you kindly help me?
 one year ago

CallistoBest ResponseYou've already chosen the best response.1
@kryton1212 Please start a new post for a new question!
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
the problem is I cannot draw picture in a new post
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
ok, let this be last question discussed in this post, agreed @kryton1212 ? for this u know how to find intercepts ?
 one year ago

CallistoBest ResponseYou've already chosen the best response.1
You can post the question a draw it in the comment
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
@hartnn that's ok. c=yintecept
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
nopes, c is y intercept in y=mx+c not here
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
to get x intercept, put y=0 in ax+by+c=0 to get y intercept, put x=0 in ax+by+c=0
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
now tell me what intercepts u get
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
....oh yes. I don't know how to find the intercept in these gaphs
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
to get x intercept, put y=0 to get y intercept, put x=0 in any graphs
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
ax+by+c=0 put y=0??? ax+c=0?
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
yes, thats right ax+c=0 x= ?
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
absolutely correct! now c/a is positive or negative ?
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
given a and c are positive....
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
so your xintercept is negative, that is it will cut x axis in negative (left) side got this ? what about yintercept ???
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
so it may be B or E. y=c/b is it E?
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
yes, y intercept is also negative, so it will cut down. and yes its E clear as to how ?
 one year ago

kryton1212Best ResponseYou've already chosen the best response.0
clear now, thank you
 one year ago

hartnnBest ResponseYou've already chosen the best response.0
make sure u ask next question in new post...
 one year ago

phiBest ResponseYou've already chosen the best response.0
@kryton1212 it would be better if you made each question a separate post.
 one year ago
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