Answer:

18√7x⁶

Step-by-step explanation:

Given the expression 7√28x⁶+4√7x⁶, we are to fund the sum in its simplest form as shown;

7√28x⁶+4√7x⁶

= 7√(7*4)x⁶+4√7x⁶

= 7*2√7x⁶+4√7x⁶

= 14√7x⁶+4√7x⁶

Factor out the like term

= 2√7x⁶(7+2)

= 2√7x⁶(9)

= 18√7x⁶

Hence the sum is equivalent to 18√7x⁶