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Wrong content on the link

https://app.dataquest.io/m/159/finding-extreme-points/2/introduction-to-derivatives

In this link, it shows that if x<1.5 slope of the tangent is 0 but it is zero at 1.20 only and all the comparisons made with 1.5 like this on this mission will turn out to be wrong kindly check once.
Capture

According to the image you have provided, the slope of the tangent equals zero only when x=1.5

When x is less than 1.5, the slope of the tangent is positive. When x is greater than 1.5, the slope of the tangent is negative. These observations are inline with link you have provided.

Can you explain where you got 1.20 and where it indicates that the slope of the tangent is 0 when x is less than 1.5? I can’t seem to find this anywhere in the mission…