Back solving a function or goal seek in R

I'm trying to learn my way around R and I need a little help. Below is a little sample of the kind of problem I am working on.

myFunction <- function(price1) {
  prices <- c(1:50)
  prices[1] <- price1
  recursiveA <- vector(length = 51)
  recursiveA[1] <- 100
  for (i in 1:50) {
    recursiveA[i+1] <- 30*prices[i] + recursiveA[i]
  }
  target <- recursiveA[51]
  return(target)
}

What I want to do is create a new function that will find the price1 value needed to yield a target value. For example in this new function I would be able to set 47320 as a parameter and it would return 300. In the first function, myFunction, a value of 300 returns a value of 47320.

How can I write a function in R to do this? Is there an existing function in R? I see through my Googling and searching on this site, a lot of people recommend the uniroot() function or optimize(). I can't figure out how to use that for something other than algebraic quadratics.

If it helps, I know that in excel I can solve this easily by using the goal seek tool. You can set a desired output and it finds the needed input from the formula(s) you define.

Please let me know if anything's unclear and I will try my best to explain further.

Any help is much appreciated. Thank you.