Answer:
x⁷⁶ + 2401
Step-by-step explanation:
When an exponent is raised to another exponent, the two exponent values are multiplied. When a number is raised to an exponent, the number is multiplied by itself that many of times.
(x¹⁹ + 7)⁴ ---->
x⁽¹⁹ ˣ ⁴⁾ + 7⁴ --->
x⁷⁶ + (7 x 7 x 7 x 7) --->
x⁷⁶ + 2401
