# 7.3ߎˉes
# }7.7ɎˉesgĂ݂
X3 <- matrix(c(1,0,0,0,1,0),3,2) 
Px <- X3%*%solve(t(X3)%*%X3)%*%t(X3)
y3 <- c(3,4,2)
y3hat <- Px %*% y3

# ϕ΍f[^ɎˉesKpꍇ
y <- candy0[,"sales"]    # ϐ̃xNgpӂ
X <- candy0[,2:3]@@@@# ϐ̍spӂ
attach(candy)
Px <- X%*%solve(t(X)%*%X)%*%t(X)  # ˉes
y2hat <- mean(sales)+ Px %*% y@@# \l͓
b2 <- solve(t(X)%*%X)%*%t(X)%*%y@ # ΉAW