Write a Java expression for the following: |x^2 + 2xy|

Math.abs(x * x + 2 * x * y)

The modulus bars mean absolute value, so the whole expression goes inside Math.abs(). Write x^2 as x * x rather than Math.pow(x, 2) — shorter and it avoids the double return type. Note that 2xy must be written 2 * x * y with both multiplication signs; Java has no implied multiplication as algebra does. Missing an operator here is the commonest slip in expression questions.