Describe the domain and range of the function. 9.
y = 2x2 + 8x +7
10.
y = -3x2 + 18x – 22
Domain:
Domain:
Range:
Range:

a² + b²= c²

24² + 7² = c²

c= 25

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