Kai Chew's answer to Clara's Secondary 4 E Maths Singapore question.
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sorry for the messy working.
explanation:
Basically, x^2 + kx + k is a U shaped curve. You can observe this from the positive coefficient of x^2.
On the other hand, y=-x^2 + 2x -4 curve is an “n” shaped curve. You can observe this from the negative coefficient of x^2.
Hence, if you draw it out, the only way for both curves to have the same tangent at their intersection point is when they intersect at their turning points.
Since the gradient at their turning points is 0, dy/dx = 0. Hence, from there u can solve the qn.
explanation:
Basically, x^2 + kx + k is a U shaped curve. You can observe this from the positive coefficient of x^2.
On the other hand, y=-x^2 + 2x -4 curve is an “n” shaped curve. You can observe this from the negative coefficient of x^2.
Hence, if you draw it out, the only way for both curves to have the same tangent at their intersection point is when they intersect at their turning points.
Since the gradient at their turning points is 0, dy/dx = 0. Hence, from there u can solve the qn.
Date Posted:
1 year ago
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