#Passo 1: dados
x <- c(10, 20, 30)
y <- c(20, 25, 45)

x2 <- x^2
#Passo 2: plotando os dados
plot(y, type="l", lwd=2, col="blue",
   xlab="Obs.", ylim=c(0,50))
lines(x, type="l", lwd=2, col="red",
     xlab="Obs.")
lines(x, type="p", lwd=2, col="black")
lines(y, type="p", lwd=2, col="black")
legend("topleft", c("x", "y"), lwd=2, col=c("blue", "red"))

plot(x, y, type="p", lwd=2, col="black", main="Scatter Plot",
     pch=16, xlim=c(0,50), ylim=c(0, 50))
abline(lm(y~x), lwd=2, col="red")


#Passo 3: estimando y = b1 + b2x
mod <- lm(y~x)
summary(mod)
yhay <- fitted.values(mod)
sum((y - yhay)^2)