quickly answers
#include <stdio.h> void printHelp () { printf ("\n"); printf ("a: a(x) = x*x\n"); printf ("b: b(x) = x*x*x\n"); printf ("c: c(x) = x^2 + 2*x + 7\n"); printf ("q: quit\n"); } void a(float x) { float v = x*x; printf (" a(%.2f) = %.2f^2 = %.2f\n", x, x, v); } // end function a void b(float x) { float v = x*x*x; printf (" b(%.2f) = %.2f^3 = %.2f\n", x, x, v); } // end function b void c(float x) { float v = x*x + 2*x + 7; printf (" c(%.2f) = %.2f^2 + 2*%.2f + 7 = %.2f\n", x, x, x, v); } // end function c int menu () { char selection; float x; printHelp (); scanf ("%s", &selection); if (selection == 'q') return 1; scanf ("%f", &x); if (selection == 'a') a(x); if (selection == 'b') b(x); if (selection == 'c') c(x); return 0; } // end function menu int main() { while (menu() == 0); printf ("... bye ...\n"); return 0; } // end main