9 



10. Interest on money loaned it fnHilatrJ by the formula 



/ / I 



In the interest (/) a continuous or a discontinuous function of /*? 

 of A' 



& esent work will be concerned for the most part 



\\ithalgebm involving only the 



power* of the varial ii algebraic equa the 



in-! --. ...M.| degree. \ - therefore given of the 



solution ami th< lie quadratic equation, presenting in 



the most in ; results \\hi.-h will be needed i: 



Analytic Geometry. The stud. -nt -li-uM become thoroughly 

 .liar with this theory, as well as with the review o! 

 ;irh follows it. 



9. The quadratic equation. Its solution. T In- most general 

 equntiot ,-0,11,1 degree, in one unknown number, may 



be written in the form 



1>f + c^ . . (1) 



where a, 6, and c are km.un numbers. This equation may 

 be solved by the method <>f "completing the square,** whi< h 



- "> 



= - |L JL V6 1 - 4 OC. . . . 



If j j .are used to denote the roots of eq. (1), they 



may be written 



j , - 6 - VP - 4 <ig /<; x 

 , and*,- -. . . . (5) 



