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Do you recognise the form:
?
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yes
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its for a straight line
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Can you rearrange into that form?
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y=8x+-4?
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Not quite, be careful with the signs
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Have another go
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What I wrote it like this:
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then*
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Which term do you need to move to the right?
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the would you divide?
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Remember we are trying to make look like
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8x
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Yes, we need to from both sides. What do you think it will look like then?
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y+8x-8x=-4 -8x ?
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Yes, which simplifies to what?
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-12?
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Okay we have . What terms do you think will cancel each other out?
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8x
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-8x
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Brilliant, so can you now simplify:
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You need 2 terms to cancel. So far we have , what will cancel that?
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would you divide -4 from -8x ?
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We can do this entirely with addition and subtraction. We know that and cancel, so what do we do with those terms in:
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subtract?
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Write out the whole equation
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I think you've got it
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y=-8x-(-4) ?
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Almost!
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which is the same as
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Rearranging can be hard at first, but I think another time we need to go through the rules. Once you're familiar with those it will be much easier.
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Do you know what the "intercepts" are?
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x and y coordinates
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x and y coordinates could be anything, Where would we find the intercepts on a graph?
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wouldn't you replace the values of x and y
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like y=-4-8(0) then simplify y=-4
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Yes!
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so wouldn't y intercept at -4
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Exactly, we also know that in the form that C will always be the intercept
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Okay, what about the x intercept?
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Remember the original form
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8
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Try and break it down into stages
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how do we rearrange that to find ?
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y=x/8?
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We are looking at the equation . I have replace with so we can find the x intercept. Just like when you set to in the last bit.
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We need to get it so that is on his own. At the moment there is an there. How can we move the to the left side?
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from both sides?
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0/-4?
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8 is a little different from earlier as it multiplying
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subtract
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Okay think of it a different way.
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We could divide both sides by 8
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to give
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8x/8x cancel out
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Yes,
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so what is the value of the x intercept?
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, or more simply
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So we could write , or more simply
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Sorry
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4
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1
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Not quite, if we make it look like this, it might be clearer
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would you divide -4/8 ?
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We could also say it in words. x equals minus 4 divided by 8.
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So lets recap
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Yes
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-0.5.
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so what value is minus 4 divided by 8?
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the intercept is , and the intercept is
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Are you comfortable drawing that?
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not really i never graphed -0.5 or other like it, how would you?
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Have you got some squared paper?
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yes
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Draw a set of axes in the middle of the page. What range should you put on the axes to make sure we get both of the intercepts in?
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bh104, I must go now. You can see an example of the graph here: http://bit.ly/I8kcFE . Look at the X and Y axes and see where the lines crosses them.
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point o -4
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ok thank you
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My pleasure. Hope it helped
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Yes thank you
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If you have any more questions then post them up
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