Shawn's answer to Ashley's Secondary 2 Maths Singapore question.
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y = k/(x-1) because it is inversely proportional to x-1 and not just x. Just sub in the values to get your k.
The second part states that when x=a, y=b just sub into the equation and get your equation first.
When y doubled this means that the new y=2b
Just expand the right hand side in terms of x first because x=a only when y=b but now your y is 2b. After you expand the left hand side you’ll get 4b^2. Note from previous equation b^2 equals to the one I boxed up and all you have to do is to sub it in the new value of y.
a>1 because if a=1 you’ll get a fraction of 1/0 which is math error. If a is smaller than one I’ll make the whole equation negative but y^2 will always be positive. Hope that helps. If you need more clarification feel free to comment here
The second part states that when x=a, y=b just sub into the equation and get your equation first.
When y doubled this means that the new y=2b
Just expand the right hand side in terms of x first because x=a only when y=b but now your y is 2b. After you expand the left hand side you’ll get 4b^2. Note from previous equation b^2 equals to the one I boxed up and all you have to do is to sub it in the new value of y.
a>1 because if a=1 you’ll get a fraction of 1/0 which is math error. If a is smaller than one I’ll make the whole equation negative but y^2 will always be positive. Hope that helps. If you need more clarification feel free to comment here
Date Posted:
3 months ago
Sorry it should be y^2 = k/(x-1) instead of y. Made a typo.
You can also use real numbers to test the solution out. Eg if y=2, what is your x value and that will be your a, after that double y and it becomes y=4, you’ll get your x value. Try using (a+3)/4 you should get back the same x value when y is doubled.
You can also use real numbers to test the solution out. Eg if y=2, what is your x value and that will be your a, after that double y and it becomes y=4, you’ll get your x value. Try using (a+3)/4 you should get back the same x value when y is doubled.
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