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

7³ · 7⁴ · 7² = 7^{3 +  4 +  2}

= 7⁹                            (Add  exponents: 3 + 4 + 2 = 9)

Product of  7³ · 7⁴ · 7² is 7⁹.