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secondary 3 | A Maths
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need help with 7 and 8c,pls explain too
b) basically is the number of points wherr they intersect.
y = mx + c is your usual equation of a straight line.
In this case your m = 2/π and c = 0.
2/π is just 2 ÷ π
2 ÷ π ≈ 0.63661977....
You know that when x = 0, y = 2/π × 0 = 0
When x = 2π, y = 2/π × 2π = 4
So for this straight line, just mark the coordinates (0,0) and (2π, 4) and join them.
If you had for example, y = 3x + 6 for the domain -3 ≤ x ≤ 10,
Sub x = -3 and x = 10 since they are the boundaries of your domain.
You'll get y = -3 and y = 36 respectively.
Plot (-3,-3) and (10,36) and join them.
Anywhere on this line, the gradient is the same.
LockB, we draw such lines as usual. If we are provided with the range say 0 to 2pi, we can just substitute these limits to find the coordinates which would be (0, 0) and (2pi, 4).
The purpose of putting a pi in the denominator of the equation of the line is so that you have a nice y-value for sketching on your graph.
As for 2/π itself, they should always be aware that π = 3.141592653...
It is a real number, and not a variable, so there's nothing to worry.
The setters could easily switch the question to another real transcendental number like e .
(though at this level we wouldn't expect things like the golden ratio (φ) = (1+√5) / 2 or Apéry's constant (ζ(3) ≈ 1.2020569031595942854...)
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