上c语言第二节课，人已疯这要怎么写啊？求解

double n,x,y,z;
n=x*x+(y*z)/2;
double a,b;
(a-b)/(a+b)+1/2;
double a,b,c,y;
y= (3.8*(b*b+a*c))/(6*a);
double a,b,c,x;
a*x*x+b*x+c;
#include<stdio.h>
#define PI 3.1415926
int main(void)
{
double r,c,s;
r=3.5;
c = 2*PI*r;
s = PI*r*r;
printf("c=%lf, s=%lf" , c,s);
return 0;
}
#include<stdio.h>
#define π 3.14
int main(void)
{
double r,h;
r=2;
h=5;
printf("area = %lf" , (π*r*r)+2*π*r*h);
return 0;
}
虽然括号多 但是能对就行