5 SCREEN 1
6 WINDOW (-17, 20)-(17, -20)
10 FOR x = -4 TO 4 STEP .007
20 y = x ^ 2
30 PSET (x, y)
40 NEXT x
50 f = 0
60 FOR x = .5 TO 4 STEP .5
70 LINE (f, 0)-(x, x ^ 2), , B
75 f = x
80 NEXT x
90 LOCATE 4, 3
100 PRINT "area under"
110 PRINT "  curve y=x^2"
120 PRINT "  from 0 to 4"
130 PRINT "  by rectangles"
135 PRINT "  and integral"
150 DEFDBL A-Z
160 a = 0
170 b = 4
180 c = 300000
190 d = (b - a) / c
200 f = 0
210 FOR x = 0 TO 4 STEP d
220 e = (x ^ 2) * d
230 f = f + e
250 NEXT x
260 LOCATE 15, 1
270 PRINT "area by rectangles ="; f
275 PRINT CHR$(179); "4"
280 PRINT CHR$(179); "0 (x^3)/3 ="; (b ^ 3) / 3
290 PRINT "Area under curve y=x^2=limit as "; CHR$(127); "x->0"
300 PRINT "of "; CHR$(228); " (x^2)"; CHR$(127); "x="
305 PRINT "   n    n"
310 PRINT CHR$(244); "4        "; CHR$(179); "4"
320 PRINT CHR$(245); "0 "; "x^2 dx="; CHR$(179); "0 (x^3)/3"