Wong Wei Jie's answer to Cheryl's Secondary 3 A Maths Singapore question.
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Using linear law concept, Y = mX + c
Since they said 1/y is plotted linearly with 1/√x,
(1/y) = m(1/√x) + c
When y = 0.25, x = 0.04,
(1/0.25) = m(1/√0.04) + c
4 = 5m + c ---> (1)
When y = 0.5, x = 1,
(1/0.5) = m(1/√1) + c
2 = m + c ---> (2)
Do simultaneous equation
(1) - (2):
2 = 4m
m = 0.5
Sub in m into (2):
c = 1.5
Therefore, (1/y) = 0.5(1/√x) + 1.5
When x = 9,
(1/y) = 0.5(1/√9) + 1.5
(1/y) = ⅙ + 1.5
(1/y) = 10/6
y = 6/10 = 0.6
Since they said 1/y is plotted linearly with 1/√x,
(1/y) = m(1/√x) + c
When y = 0.25, x = 0.04,
(1/0.25) = m(1/√0.04) + c
4 = 5m + c ---> (1)
When y = 0.5, x = 1,
(1/0.5) = m(1/√1) + c
2 = m + c ---> (2)
Do simultaneous equation
(1) - (2):
2 = 4m
m = 0.5
Sub in m into (2):
c = 1.5
Therefore, (1/y) = 0.5(1/√x) + 1.5
When x = 9,
(1/y) = 0.5(1/√9) + 1.5
(1/y) = ⅙ + 1.5
(1/y) = 10/6
y = 6/10 = 0.6
Date Posted:
3 years ago
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