Main.cc: In function 'int main()':
Main.cc:10:28: error: invalid operands of types 'double' and 'double' to binary 'operator^'
printf("%.5lf",a*x^3+b*x^2+c*x+d);
^
Main.cc:10:25: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
printf("%.5lf",a*x^3+b*x^2+c*x+d);
^