Please Explain

[Atonio79]

1. x^4 + y^4=100, then the greatest possible value of x is between
a. 0 and 3
b. 3 and 6
c. 6 and 9
d. 9 and 12
e. 12 and 15

2. If n is a multiple of 5 and n=(p^2)*q, where p and q are prime numbers, which of the following must be a multiple of 25?
a. p^2
b. q^2
c. pq
d. p^2q^2
e. (p^3)q

[Dynamo]

1) IMO B

for this sum you need to minimize y the minimum value of y can be 0 here becase any -tive number taken will become positive since y^4

so the x = (100)1/4 = 3.16

so the value of x is between 3 and 6

2. IMO d

n = (p^2)(q) now either q can be 5 or p we dont know

so among the options the safest bait is p^2q^2