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 August 17th, 2017, 12:26 PM #1 Newbie   Joined: Aug 2017 From: glasgow Posts: 2 Thanks: 0 Straight Line workings Hi, Need help with the following please: equation is Y=3x -1 I have two rows X and Y and trying to work the answers for the Y coordinate, struggling when I get to the minus figures. X -3 -2 -1 0 1 2 3 Y ? ? ? -1 2 5 8 What are the (Y) answers for -1, -2 and -3 To get the first answer 8, I done 3x3-1 =8 and 3x2-1 = 5 Many thanks Last edited by jl1974; August 17th, 2017 at 12:28 PM. August 17th, 2017, 12:34 PM   #2
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Quote:
 Originally Posted by jl1974 Hi, Need help with the following please: equation is Y=3x -1 I have two rows X and Y and trying to work the answers for the Y coordinate, struggling when I get to the minus figures. X -3 -2 -1 0 1 2 3 Y ? ? ? -1 2 5 8 What are the (Y) answers for -1, -2 and -3 To get the first answer 8, I done 3x3-1 =8 and 3x2-1 = 5 Many thanks
just continue as you have done

for $x=-1$

$y = 3(-1) - 1 = -3 -1 = -4$

I'm sure you can continue for $x=-2,~-3$ August 17th, 2017, 12:48 PM #3 Newbie   Joined: Aug 2017 From: glasgow Posts: 2 Thanks: 0 Thanks for response. This is for my daughter, can you explain like my example if possible please. like 3 times 3 = 9 minus 1 = 8 Can you tell me what the answer is for -1? Thanks. Last edited by jl1974; August 17th, 2017 at 01:08 PM. August 17th, 2017, 02:47 PM   #4
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 Originally Posted by jl1974 3 times 3 = 9 minus 1 = 8
Be careful how you use equals signs - it is not true that 3 times 3 equals 9 minus 1. You could instead separately state that 3 times 3 = 9, and that 9 minus 1 = 8. August 17th, 2017, 04:00 PM   #5
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 Originally Posted by jl1974 Thanks for response. This is for my daughter, can you explain like my example if possible please. like 3 times 3 = 9 minus 1 = 8 Can you tell me what the answer is for -1? Thanks.
3 times -1 minus 1 =

-3 minus 1 =

-4 September 13th, 2017, 09:53 AM #6 Newbie   Joined: Sep 2017 From: malaysia Posts: 1 Thanks: 0 Hi everyone, please help me to solve this equation, my brain stuck already... given f(x) = 2x - 6, determine value of k if inverse function f(2k) = f(k+1). Please help me with the detailed solution. Last edited by skipjack; September 13th, 2017 at 12:30 PM. September 13th, 2017, 12:35 PM #7 Global Moderator   Joined: Dec 2006 Posts: 20,635 Thanks: 2080 The function f(x) = 2x - 6 has inverse g(x) = x/2 + 3. As g(2k) = k + 3 and f(k+1) = 2k + 2 - 6 = 2k - 4, these are equal for k = 7. Thanks from abdul hadi harun September 13th, 2017, 11:55 PM   #8
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Quote:
 Originally Posted by jl1974 Hi, Need help with the following please: equation is Y=3x -1 I have two rows X and Y and trying to work the answers for the Y coordinate, struggling when I get to the minus figures. X -3 -2 -1 0 1 2 3 Y ? ? ? -1 2 5 8 What are the (Y) answers for -1, -2 and -3 To get the first answer 8, I done 3x3-1 =8 and 3x2-1 = 5 Many thanks
Quote:
 Originally Posted by jl1974 Thanks for response. This is for my daughter, can you explain like my example if possible please. like 3 times 3 = 9 minus 1 = 8 Can you tell me what the answer is for -1? Thanks.
Your Equation is,
$\displaystyle y=3x-1$

So,
If, $\displaystyle x=3$
Then, $\displaystyle y=3\times3-1=9-1=8$

$\displaystyle x=2$
Then, $\displaystyle y=3\times2-1=6-1=5$

$\displaystyle x=1$
Then, $\displaystyle y=3\times1-1=3-1=2$

$\displaystyle x=0$
Then, $\displaystyle y=3\times0-1=0-1=-1$

$\displaystyle x=-1$
Then, $\displaystyle y=3\times{-1}-1=-3-1=-4$

$\displaystyle x=-2$
Then, $\displaystyle y=3\times{-2}-1=-6-1=-7$

$\displaystyle x=-3$
Then, $\displaystyle y=3\times{-3}-1=-9-1=-10$ Tags line, straight, workings Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Elliot11 Algebra 2 May 25th, 2016 10:33 AM shalikadm Algebra 3 January 24th, 2012 10:48 PM outsos Algebra 7 December 23rd, 2010 07:15 PM Kiranpreet Algebra 3 August 10th, 2008 07:45 AM Kiranpreet Algebra 2 August 9th, 2008 09:29 AM

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