EN
Let 1 < k < 33/29. We prove that if λ₁, λ₂ and λ₃ are non-zero real numbers, not all of the same sign and such that λ₁/λ₂ is irrational, and ϖ is any real number, then for any ε > 0 the inequality $|λ₁p₁ + λ₂p²₂ + λ₃p₃^k + ϖ | ≤ (max_j p_j)^{-(33-29k)/(72k)+ε}$ has infinitely many solutions in prime variables p₁, p₂, p₃.