Identify which of the twelve basic functions listed below fit the description given. y = x, y = x2, y = x3, y = [xl, y = y = et, y = Vä, y = Inx, y= sinx, y = cosx, y = int(x), y = ite
1
C.
The four functions with local minima.
a. y = x2, y = sin x, y = cos x, y = |x||
b.
1
y = sin x, y = cos x, y = |x|, y =
1 + e-*
y = Vxy = sin x, y = cos x, y = ln x
d. y=x2, y = x3, y = sin x, y = cos x

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4