Review question

# When does this function of two variables have a minimum? Add to your resource collection Remove from your resource collection Add notes to this resource View your notes for this resource

Ref: R9671

## Question

The variables $x$ and $y$ are such that $x^4y=8$. A third variable $z$ is defined by $z=x+y$.

Find the values of $x$ and $y$ that give $z$ a stationary value and show that this value of $z$ is a minimum.