问如何多次运行“单根”以求两个函数的交点

EN

g1 <- function(x,y){x^2/y^2}
f1 <- function(x, y){ x^2-3*y+g1(x)}
f2 <- function(x, z){ 4*z-x^2 } 
f <- function(x, y, z){ 
x^2-3*y-(4*z-x^2) 
} 

z <- 5; 
y <- 3 

rr=uniroot(f=f, y=y, z=z, interval=c(0,10))$root 
rr

z <- c(1, 2, 3) 
y <- c(3, 4, 5) 

rr=uniroot(f=f, y=y, z=z, interval=c(0,10))$root 

 f() values at end points not of opposite sign 
In addition: Warning messages: 
1: In if (is.na(f.lower)) stop("f.lower = f(lower) is NA") : 
  the condition has length > 1 and only the first element will be used 
2: In if (is.na(f.upper)) stop("f.upper = f(upper) is NA") : 
  the condition has length > 1 and only the first element will be used