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equations together, divide the equation propofed by 
their product, and proceed as abovcmentioned. 
9. The greateft negative coefficient, of any equa- 
tion (confidered as affirmative) and increafed by uni- 
ty always exceeds the greateft affirmative root of the 
equation. Ard therefore, 
10. If for the unknown quantity (*•) in the e- 
quation, you put that coefficient taken affirmatively 
and increafed by unity minus x, all the roots of the 
equation will be rendered affirmative. If )0U do 
this, you need only ufe fuch rulers, as are defcribed 
in the firft figure, whofe centers are at their extremi- 
ties, and fo one fort of rulers will be fufficient for all 
cafes. For you may obferve, thofe in the lecond figure 
are different from the other, as to their centers. 
j 1 . If, when you have made all the roots of your 
equation affirmative, you would avoid removing the 
ruler M M to the right hand fide of R R, which 
might be attended with inconveniency ; that is, if 
you would have all the roots of your equation fall 
between O and T, that is, between nothing and 
unity, inftead of the unknown quantity x in your laft: 
equation, put x multiplied by the greateft: negative 
coefficient therein confidered as affirmative and in- 
creafed by unity ; for inftance, if the greateft nega- 
tive coefficient in the equation be minus 9, put 10* 
inftead of every x in the equation, and you will 
have a new equation, all whofe roots ffiall fall upon 
the line O T unproduced ; for then they will be left 
than unity, that is, than D or OT : but when the 
roots are thus found, each of them muft be mul- 
tiplied by that coefficient increafed by unity, that is, 
in the above inftance, by 10 , becaufe putting iox 
