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If the graph of the quadratic function f(x) = x^2 + dx +3d has its vertex on the x axis what are the possible values of d? What if f(x) = x^2 + 3dx +1?
 one year ago
 one year ago
If the graph of the quadratic function f(x) = x^2 + dx +3d has its vertex on the x axis what are the possible values of d? What if f(x) = x^2 + 3dx +1?
 one year ago
 one year ago

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mukushlaBest ResponseYou've already chosen the best response.1
complete the square for x^2 + dx +3d to get its vertex
 one year ago

meera_yadavBest ResponseYou've already chosen the best response.1
mukushla is right :) try doing ...
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
I have the answers. Easily accessible in the back of the book. How to solve it is the problem. When you say complete the square what do you mean? I've been trying x^2 + dx +3d = ax^2 + (2ah)x+ (ah^2+k) And trying to identify the vertex.. that waayy... But what do you mean by complete the square?
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
the vertex of quadratic equation is given by (b/2a, cb^2/4a) since it has vertex on X axis therefore y ordinate =0 . hence cb^2=0
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
Thanks! I'll try it again.
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
in 1st case the value of d=0 and 3 in 2nd case d=1/3 and 1/3
 one year ago

mukushlaBest ResponseYou've already chosen the best response.1
@jenejij take a look http://www.mathsisfun.com/algebra/completingsquare.html
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
Oh okay. I know how to "complete the square" haha. Got it. =)
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
Actually  still having problems.. =/ I don't think x=3. x= 0, and x= 12.
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
x=12 is not right answer
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
thats what the answer in the back of my text book is... but I don't know how to get there.
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
what is the final answer of first part?
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
d = 0 and d= 12. According the the textbook...
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
and for second part ??
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
\[d = + or  2 / \sqrt{13}\]
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
I got the answer: plz check it
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
the value of x coordinate of vertex is given by b/2a; from the given question we have a=1 b=d c=3d substituting the values in b/2a we have d/2
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
to find y ordinate substitute this value in the given eq. we have dw:1341572810912:dw
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
I circled that thing.. is it d?
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
since it has vertex on x axis thus y=0 hence we have d^2/4  d^2/2 +3d = 0 on solving we have d=0 and 12
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
have u understood ??
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
similarly u can do second part .. plz do it and tell me have u got the answer or not
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
okay I will work on it
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
give me a medal .........lol
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
\[x^2 + 3dx  d^2 +1 then 0 = (d/2)^2 +3d(d/2)  d^2 + 1 \]
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
\[(d/4)^2 + 3d^2/2 d^2 +1 = 0 \]
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
no; for second part u again need to find the x coordinate and follow the same steps
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
since it was a different equation
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
okay let me try again. toss that grain of salt my way (I've been working all night.. it's 4:21 am) I'm not usually this bad haha
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
no problem: from which country u r from ??
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
okay so then is 3d = b/2a?
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
I can't think. I have to do this in the morning. Thanks so far.
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
give me 1 min, let me tell you
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
in second part : a=1 b=3d c=1 now subs. in b/2a u have 3d/2
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
okay. I was on the right track. but not quite there.
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
then put this value of x in original equation x^2+3dx+1=0dw:1341574077931:dw
 one year ago

jenejijBest ResponseYou've already chosen the best response.1
Okay. I see the answer. And I understand, but without sleep I won't reeeally get it. Again thank you for your help.
 one year ago

k.rajabhishekBest ResponseYou've already chosen the best response.1
bye i had sent u mail plz check it
 one year ago
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