9.2  a) Plot[Piecewise[{{x+1, x<=1}, {x-1, x>1}}],{x,0,3}]

9.5  c) limit (cos x) / x where x to pi
     d) limit x*sin(1/x) where x to 0
     g) limit(1/x-1/x^2) where x to 0
     j) limit |x|/x where x to 0

9.6  c) limit (x^2+x)/(x^3+1) where x to -1
     d) limit (x^2-2x-3)/(3-x) where x to 3
     i) limit (5y^3+8y^2)/(3y^4-16y^2) where y to 0
     j) limit (x+1)/(sqrt(x^2-1)) where x to -1
     j2) limit (x+1)/(sqrt(x^2-4)) where x to -1

9.7  a) limit (sqrt(x)-1)/(x-1) where x to 1
     f) limit (x-sqrt(x^2-x)) where x to infty
        plot (x-sqrt(x^2-x)) where x from 0 to 100
     g) limit (x-sqrt(x^2-x)) where x to infty
        plot (x-sqrt(x^2-x)) where x from 0 to 100


9.8  a) limit 3x/(x-4) where x to infty
	plot 3x/(x-4) where x from 0 to 100
     b) limit x^2/(x+1) where x to infty
	plot x^2/(x+1) where x from 0 to 100
     d) limit sqrt(x^2+1)/(x) where x to -infty
        plot sqrt(x^2+1)/(x) where x from -1 to -100
     h) limit 1/(x^2-7x+1) where x to infty
        plot 1/(x^2-7x+1) where x from 0 to 100

9.9  b) limit sin(4x)/x where x to 0
     e) limit (1-cos x)/x^2 where x to 0
     i) limit (sin(3x))/x where x to infty
        plot (sin(3x))/x where x from 1 to 100
     l) limit (x/(1+x))^x where x to infty
        Plot[{e^-1,(x/(1+x))^x]
     m) limit (1-x)^(3/x) where x to 0
        Plot[{e^-3,(1-x)^(3/x)}]
     n) limit ((x+1)/(x-2))^(3x-2) where x to -infty
        plot ((x+1)/(x-2))^(3x-2)  plot e^9 where x from -10000 to 0

9.10 a) limit (2-sqrt(x+3))/(x^2+x-2) where x to 1
     b) limit (x+2)/(1-sqrt(x+3)) where x to -2
     d) limit (sqrt(x^2-4x)+x) where x to -infty
     e) limit (x^2*sin(1/x))/(sin x) where x to 0
     i) limit (cos x)/(cos x -1) where x to 0