13.2	a)	integrate (3x) dx from 0 to 3
	 	Plot[3x,Piecewise[{{0, 0<=x<=1}, {3, 2>x>1}, {6, 3>x>2}}], {x, 0, 3}]
		Plot[3x,Piecewise[{{3, 0<=x<=1}, {6, 2>x>1}, {9, 3>x>2}}], {x, 0, 3}]
		Plot[3x,Piecewise[{{1.5, 0<=x<=1}, {4.5, 2>x>1}, {7.5, 3>x>2}}], {x, 0, 3}]
	c)	integrate (4x-x^2) dx from 1 to 4
		Plot[4x-x^2,Piecewise[{{4*1.0-1.0^2, 1.5>x>1}, {4*1.5-1.5^2, 2>x>1.5}, {4*2.0-2.0^2, 2.5>x>2}, {4*2.5-2.5^2, 3>x>2.5}, {4*3.0-3.0^2, 3.5>x>3}, {4*3.5-3.5^2, 4>x>3.5}}], {x, 1, 4}]
		Plot[4x-x^2,Piecewise[{{4*1.5-1.5^2, 1.5>x>1}, {4*2.0-2.0^2, 2>x>1.5}, {4*2.5-2.5^2, 2.5>x>2}, {4*3.0-3.0^2, 3>x>2.5}, {4*3.5-3.5^2, 3.5>x>3}, {4*4.0-4.0^2, 4>x>3.5}}], {x, 1, 4}]
		Plot[4x-x^2,Piecewise[{{4*1.25-1.25^2, 1.5>x>1}, {4*1.75-1.75^2, 2>x>1.5}, {4*2.25-2.25^2, 2.5>x>2}, {4*2.75-2.75^2, 3>x>2.5}, {4*3.25-3.25^2, 3.5>x>3}, {4*3.75-3.75^2, 4>x>3.5}}], {x, 1, 4}]
	d)	integrate sqrt(x) dx from 1 to 4
		Plot[sqrt(x), Piecewise[{{sqrt(1), 2.0>x>1.00}, {sqrt(2), 3.0>x>2.00}, {sqrt(3), 4.0>x>3.00}}], {x, 1, 4}]
		Plot[sqrt(x), Piecewise[{{sqrt(2), 2.0>x>1.00}, {sqrt(3), 3.0>x>2.00}, {sqrt(4), 4.0>x>3.00}}], {x, 1, 4}]
		Plot[sqrt(x), Piecewise[{{sqrt(1.5), 2.0>x>1.00}, {sqrt(2.5), 3.0>x>2.00}, {sqrt(3.5), 4.0>x>3.00}}], {x, 1, 4}]

13.3	a)	plot x^2, 2-x
		integrate 2-x-x^2 dx from -2 to 1
	b)	plot sqrt(4-x^2) where x from -2 to 2
		integrate sqrt(4-x^2) dx from -2 to 2
	c)	plot x^2,x^3 where x from -0.25 to 1.25
		integrate x^2-x^3 dx from 0 to 1
	d)	plot x^2/4,x,1 where x from -2 to 1
		integrate x-x^2/4 dx from 0 to 1
	f)	plot x^3/3-x, x/3
		integrate |x/3-(x^3/3-x)| dx from -2 to 2

13.4	a)	integrate (x/2+3) dx from -2 to 4
	b)	integrate sqrt(9-x^2) dx from -3 to 3
	c)	integrate 1-|x| dx from -1 to 1
	d)	integrate (1+sqrt(1-x^2)) dx from -1 to 1
					
	 
13.5		plot x^3,(x-1)^3 where x from 0 to 2

13.7 		plot x-x^2

13.8	a)	integrate 2x^2+1 dx from -3 to 2
	b)	integrate (x+5)/(x^2) dx from -5 to -1
	d)	integrate sin^2(x/2) dx from -pi/2 to pi/2
	e)	integrate (3x^4+6x^2+1)/(x^2+1)dx from -1 to 1
	f)	integrate ((sin (2x))^3)/((cos x)^3) from -pi/3 to pi/3