some explain step by step how to solve problems

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nebbercracker
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#1
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#1
So these are two questions on a past paper I am stuck with. One is inverse proportion and the other is simultaneous equation. Please could someone explain step by step how to solve them ?Inverse proportionh is inversely proportional to the square of rwhen r =5 , h=3.4find the value of h when r=8simultaneous equationx(squared) + y(squared) = 9x + y = 2help with these questions will be much appreciated
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Vav Sartrean Po
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#2
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Write out the simultaneous equation onto paper and then insert a image of it please or write more clearly. I cannot really read it. Be like x^2 etc
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nebbercracker
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#3
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(Original post by Marshall Taylor)
Write out the simultaneous equation onto paper and then insert a image of it please or write more clearly. I cannot really read it. Be like x^2 etc
ok gimme 5 minutes
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nebbercracker
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(Original post by Marshall Taylor)
Write out the simultaneous equation onto paper and then insert a image of it please or write more clearly. I cannot really read it. Be like x^2 etc

heres a picture
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BekahTalc
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#5
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I think for the first one:
INVERSE PROPORTION
the statement is h= k/r^2
Then, you substitute the numbers into the equation so it looks like: 3.4 = k/5^2 (5 squared is 25)
After substituting, you rearrange the equation so that k is on one side of the equal sign and the numbers are on the other. This looks like k= 3.4 * 25
This equals 85, but you arent finished yet

You asked what h was when r=8,
so you substitute r=8 into the formula h=85/r^2 which means you will have to square 8 (64)
This would lead to the equation looking like h=85/64 which is 1.328125. Round that to 3sf or whatever degree of accuracy it tells you. THE ANSWER IS 1.33 (3 SF)

PLEASE CHECK IF THIS IS RIGHT - i will be extremely embarrassed if it isnt
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FrostShot
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#6
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#6
(Original post by nebbercracker)
heres a picture
1) Using your 2nd equation, write y in terms of x, so y = 2 - x

2) Subsitute (2-x) instead of y back into your first equation, then solve the quadratic.

3) Find the corresponding y value for each x using your 2nd equation.
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Vav Sartrean Po
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(Original post by nebbercracker)
heres a picture
Firstly, label the things 1 and 2. Proceed by squaring 2 so it'll make it x^2+y^2=4 and then just solve. But if it's a quadratic, you'll have to use a different method that FrostShot has recommended.
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FrostShot
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(Original post by Marshall Taylor)
Firstly, label the things 1 and 2. Proceed by squaring 2 so it'll make it x^2+y^2=4 and then just solve.
Squaring doesn't work like that :facepalm:
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nebbercracker
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#9
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#9
thanks everyone , much appreciated
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Vav Sartrean Po
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#10
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#10
(Original post by FrostShot)
Squaring doesn't work like that :facepalm:
It does if you want the wrong answer
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