How do you solve (a-1)/a>0a1a>0 using a sign chart?

1 Answer
Oct 14, 2017

The solution is a in (-oo,0) uu (1,+oo)a(,0)(1,+)

Explanation:

Let f(a)=(a-1)/af(a)=a1a

The sign chart is

color(white)(aaaa)aaaaaacolor(white)(aaaa)aaaa-oocolor(white)(aaaaaaaa)aaaaaaaa00color(white)(aaaaaaaa)aaaaaaaa11color(white)(aaaa)aaaa+oo+

color(white)(aaaa)aaaaaacolor(white)(aaaaaaaaa)aaaaaaaaa-color(white)(aaaa)aaaa||color(white)(aaaa)aaaa++color(white)(aaaa)aaaa++

color(white)(aaaa)aaaaa-1a1color(white)(aaaaaa)aaaaaa-color(white)(aaaa)aaaa#color(white)(aaaaa)-#color(white)(aaaa)aaaa++

color(white)(aaaa)aaaaf(a)f(a)color(white)(aaaaaaa)aaaaaaa++color(white)(aaaa)aaaa||color(white)(aaaa)aaaa-color(white)(aaaa)aaaa++

Therefore,

f(a)>0f(a)>0, when a in (-oo,0) uu (1,+oo)a(,0)(1,+)

graph{(x-1)/x [-16.02, 16.01, -8.01, 8.01]}