Fernando's family traveled 272 miles on a road trip last weekend. they drove for four hours. what was the rate at which fernando's family traveled? write and solve a multiplication equasion.

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

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8