C语言编程 编写函数用以求表达式(x)2-5x+4的值,x作为参数传送给函数.调用此函数求:

表达式是 y1=2^2-5*2+4
y2=(x+15)^2-5*(x+15)+4
y3=(sinx)^2-5*sinx+4 是不是？？？我也需要答案 那哥们说把式子加到哪、？？

式子看不懂，你自己加到function吧
#include<stdio.h>
function(int a)
{
y1=2*2-5*2
}
int main()
{
int x;
while(scanf("%d",&x)!=EOF)
{
function(x);
}
return 0;
}

#include <stdio.h>
#include <math.h>
double sum1(double x)
{double y1;
y1=(x-1)*(x-4);
return y1;
}
double sum2(double x)
{double y2;
y2=(x+15-1)*(x+15-4);
return y2;
}
double sum3(double x)
{double y3;
y3=(sin(x)-1)*(sin(x)-4);
return y3;
}
main()
{double x,y1,y2,y3;
printf(" y1=x^2-5x+4 \n y2=(x+15)^2-5(x+15)+4 \n y3=sin^2x-5sinx+4 \n请输入x求y1、y2、y3的值:");
scanf("%lf",&x);
printf("解: \n y1=%lf \n y2=%lf \n y3=%lf \n",sum1(