Mahler ’ s measure : proof of two conjectured formulae

In this note we prove the two formulae conjectured by D. W. Boyd [Experiment. Math. 7 (1998), 37-82], m(y(x + 1) + y(x + 6x + 1) + (x + 1)) = 8 3 L ′ (χ−4,−1), m(y(x + 1) + y(x − 10x + 1) + (x + 1)) = 20 3 L ′ (χ−3,−1), where m denotes the logarithmic Mahler measure for two-variable polynomials.