QN's answer to QN's Junior College 1 H1 Maths Singapore question.
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Do you mean the curve is like this, hence it does not touch the x-axis and hence it does not have any real roots, therefore b^2-4ac < 0?
Date Posted:
4 years ago
Exactly...
You can try the Desmos graphing calculator online
Plot y = x² + (k - 2)x + (k + 1)
There will be a slider function for you to adjust the value of k. Change it accordingly and see how the curve changes.
You'll notice that when you set k to anything between 0 and 8 (not inclusive), the curve never intersects the x-axis.
Very good for visualisation.
To understand why b² - 4ac < 0, you can revisit my explanation of the quadratic formula in your earlier question.
Plot y = x² + (k - 2)x + (k + 1)
There will be a slider function for you to adjust the value of k. Change it accordingly and see how the curve changes.
You'll notice that when you set k to anything between 0 and 8 (not inclusive), the curve never intersects the x-axis.
Very good for visualisation.
To understand why b² - 4ac < 0, you can revisit my explanation of the quadratic formula in your earlier question.
That’s cool. Thanks!
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