Submitted by Erik on Wed, 12/07/2016 - 16:39
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In the solutions file it says that the equation y = x^4 - 6x^2 + 8x + b has one root when b=1. Shouldn't be b=24 because that the turning point is in (-2, -24) for y=x^4 - 6x^2 + 8x?
Submitted by Erik on Wed, 12/07/2016 - 16:39
In the solutions file it says that the equation y = x^4 - 6x^2 + 8x + b has one root when b=1. Shouldn't be b=24 because that the turning point is in (-2, -24) for y=x^4 - 6x^2 + 8x?
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Yep! Well done for spotting
Yep! Well done for spotting that. $x^4 - 6x^2 + 8x + 24$ has a repeated root at $x=-2$ and two other complex roots (because the other minimum stationary value is above the $x$-axis).
Thanks!
I've changed the solutions file. Many thanks for pointing it out!