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avatar+1124 

hi good people!.. smiley

 

I am given g(x)=a.bx+q

 

points on the graph are C(0;1) and E(1;13)

 

Determine a, b and q.

 

Okay, I know q is the y-intercept, so that is 1

so, now we plug in the values of any point to calculate b.

If the "b" was alone, I would be able to do it, but there is an "a" multiplied with the "b" as well....uhm, I'm slightly confused...can anyone please teach me the way?..

 

I do thank you all!

 Feb 22, 2019
 #1
avatar+118713 
0

1=a+qq=1a

 

 

13=ab1+q13=ab+qb013=ab+1a3b(13)=3b(ab+1a)b=3a+3b3ab0=3a+4b3aba and b both equal 0 or3a(1b)=4b3a(b1)=4ba=4b3(b1)b1

 

If    b =1    then

g(x)=a+qg(x)=a+1ag(x)=1

but then point G is not on the curve so  b cannot equal 1

 

So we have

 

.q=1aa=4b3(b1)whereb1b0

 

PLUS, I am not so sure that b can be negative........   

The graph would be very broken if b was negative, I am not sure how much that matters.

Maybe another mathematician would like to comment here. 

 

Anyway ,...There is no single solution for this.

 

Here is the graph.

 

https://www.desmos.com/calculator/bqqgr7eyms

 

Here is the graph.

 Feb 22, 2019
 #2
avatar+1124 
+1

Hi Melody,

 

According to the handbook, "b" can never be negative. It can only be either a fraction between 0 and 1, or greater than 1. Okay, so this I accept. There is an example in the book on a similar sum, but it is not clear to me. By the way it looks, it appears the "a" is disregarded and "b" is calculated. I followed that aproach and found "b" to be 12,

I then substituted this also into the equation and found "a" to be -1. But I'm not sure if that was the right way to go about it?

juriemagic  Feb 22, 2019
edited by juriemagic  Feb 22, 2019
 #3
avatar+118713 
-1

But my graph shows that a can vary as well.   frown

 

https://www.desmos.com/calculator/bxstlnfsa5

Melody  Feb 22, 2019
 #4
avatar+1124 
+1

yes, I saw that, thank you so much for your time...I do apreciate!..as always!.. smiley

juriemagic  Feb 22, 2019

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