algebra???
hey ya’ll im stuck on these 3 algebra questions i dont understand them 100% and i need some help so if you can please help me. 10points plus best answer. thanks so much
it says to write an equation for the direct variation that includes the given point.
(7, -2)
y = -2/7 x
y = 7x x
y = x – 9
y = 2x – 16
(-3, -6)
y = -2x
y = 2x
y = x – 3
y = 1/3 x – 5
(-4, -5)
y = x
y = 2x + 3
y = x – 1
y = 5/4 x
(Note: all the possible answers that look like this 1/7 are fractions)
direct variation: y varies directly as x, or y is directly proportional to x, if there is a non-zero constant k (meaning k cannot equal zero) y=k times x, so in your 3rd problem i’m guessing that you use your points, (x,y) which are (-4, -5) -4 is x and y is -5. so the first part would be y=x, which is the same as saying y=whatever x equals, so y= -4
in the 2nd part y=2 times whatever x is (-4) then add 3, so y= -5,
part 3: y=x -1 would be: y= -4 -1 which is -5
y= 5/4x so you multiply 5/4 times x which would equal 5 times 5 all over 4 which equal 20/4 then divide y=5
i’m not sure if i’m doing this right.
hope this helps, i’m not quite sure what you’re really asking for.
October 18th, 2009 at 11:02 pm
Good luck! lol sorry I’m not help I suck at math!
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October 18th, 2009 at 11:07 pm
would you just subsitute the x for the x and the y for the y for example (7, -2) 7 would be x and -2 would be y..try that for each one and it should solve the problem
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October 18th, 2009 at 11:34 pm
direct variation: y varies directly as x, or y is directly proportional to x, if there is a non-zero constant k (meaning k cannot equal zero) y=k times x, so in your 3rd problem i’m guessing that you use your points, (x,y) which are (-4, -5) -4 is x and y is -5. so the first part would be y=x, which is the same as saying y=whatever x equals, so y= -4
in the 2nd part y=2 times whatever x is (-4) then add 3, so y= -5,
part 3: y=x -1 would be: y= -4 -1 which is -5
y= 5/4x so you multiply 5/4 times x which would equal 5 times 5 all over 4 which equal 20/4 then divide y=5
i’m not sure if i’m doing this right.
hope this helps, i’m not quite sure what you’re really asking for.
References :
October 19th, 2009 at 12:12 am
it’ s easy,man.. example, let’s take (7, -2)
y=x-9
sybstitute x which is equal to 7:
y=7-9
y=-2
taking y which is equal to -2:
-2=x-9
x=-2+9
x=7
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October 19th, 2009 at 12:37 am
y=-2
x=7
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October 19th, 2009 at 12:42 am
firstly this is a direct variation question and direct variation means: y varies directly as x, or y is equal to x, if there is a non-zero constant, say a. Therefore y=a times x. So your problems is only to calculate this unknown constant from the given points to make that statement/equation true. Already you have the answers and you only need to pick which one i.e. for the first, your points are (7;-2). It implies when x=7 then y=-2. Therefore the direct variation equation y=ax and solving for a looks like this:
-2=7a hence your constant a=-2/7. The final equation becomes y= -2/7 x, which is the first one. doing the same for the other cases gives you y=2x and y=5/4x.
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