Consider the multiple linear regression model (for the ith sample),
$y_i = \beta_0 + \beta_1 x_{1i} + \beta_2 x_{2i} + \epsilon_i$,
where $x_{1i}$ denotes Leptin, $x_{2i}$ denotes Glucose, $y_i$ denotes HOMA, and $\epsilon_i$ is the random error.
Use lm to fit the above model. Find the estimate for $\beta_1$.