Is there a typo in the below R code, getting error as invalid arugument to unary operator

```
ds = dm %>% mutate_all(function(x) - factor * x ) %>%
mutate(intercept = coef(m.fit)[1], intercept = offset - factor * intercept )
```

Error message Error in mutate_impl(.data, dots) : Evaluation error: invalid argument to unary operator. Thanks in advance