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secondary 4 | A Maths
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ky
Ky

secondary 4 chevron_right A Maths chevron_right Singapore

Hi I need help with qn 2ii

Date Posted: 3 years ago
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Ryan Patel
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Hope this helps!
ky
Ky
3 years ago
But the discriminant of the gradient is nt lesser or equals to 0
Ryan Patel
Ryan Patel
3 years ago
Ryan Patel
Ryan Patel
3 years ago
Hi, it is, maybe you have done something wrong in your calculations?

dy/dx = 5x^2/2-4x-15≥-83/5

simplifying gives you (x-0.8)^2 which, if you sketch the graph, touches the x axis and is always above it. Hence, it is ≥0 which agrees with what we want to show: that f’(x)≥0