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So, here's a critical thinking problem that is giving me trouble. For the function
f(x) = x^3 - 3x^2 + x + 4
find "k" such that f(x) has only one tangent line of slope "k"
All I've done so far is taken the derivative to be
f'(x) = 3x^2 - 6x + 1
I've just never seen a problem similar to this one and I'm stumped. Any ideas?
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set k = f'(x) k = 3x^2 -6x +1 solve for k for such k that there is only one solution.
in other words find a discriminant that is 0
discriminant = b^2-4ac (-6)^2 - (4)(1)(k) find k such that the above expression = 0 = 36-4k k = 9
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Except the answer given to us was k = -2, although i kind of understand the process now.
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Okay I got it.
b^2-4ac=0 36-4(3)(1-k)=0 36-12(1-k)=0 36-12+12k=0 24+12k=0 k = -2
Thanks.
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oh oops i forgot the 3 =a
ma bad
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