Answer:
24y^15 - 24y^10 + 7
Step-by-step explanation:
f(2y^5)
= 3(2y^5)^3 - 6(2y^5)^2 +7
= 3(8y^15) - 6(4y^10) + 7
= 24y^15 - 24y^10 + 7
