Since base is common,apply the product of powers property: a^m·aⁿ= a^{m + n}.

x² · x² · x¹ = x^{2 + 2 + 1}

= x⁵                            (Add  exponents: 2 + 2 + 1 = 5)

The product of  x² · x² · x¹ is x⁵.