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The angles of a triangle must add up to 180 degrees. But this triangle’s angles add up tp 170 degrees. Therefore, impossible!
You have to change the variable, u=3x and from this can derivate u and get du=3, so the derivate for e^u is u'*e^u so the answers is 3e^3x
He would walk 2.125 miles or 2 1/8 miles in one hour