Explanation

For x > 0, log₁₀x² = 2log₁₀x, so the left side is log₁₀x + 2log₁₀x = 3log₁₀x. The equation becomes 3log₁₀x = 2log₁₀x + 1, giving log₁₀x = 1. Hence x = 10, which is option (d).