When the polynomial x3 − 7x2 + ax + 3 is divided by x − 3, the remainder is –18. using synthetic division, determine the value of a.
–5
–17
5
17

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

not sure but it may be b, as i said i'm not sure.

c. 6tan80

step-by-step explanation: