Which monomial is a perfect cube?

49p9q3r24

81p12q15r12

121p9q3r6

343p6q21r6

Ok, so dis is wat yo do

xyz = (x) (y) (z)

x^3y^3z^3 = (x^3) (y^3) (z^3)

split it up, if one is not a perfect cube, it is wrong

remember

(x^n) ^m=x^ (mn)

so

(x^n) ^3 is a perfect cube (for nicety, make sure that n is a whole number)

basically see which exponents are multiplules of 3

first one

49 is 7^2, not perfect cube

wrong

2nd one

81=3^4, not a perfect cube

wrong

3rd one

121=11^2,

wrong, not perfect cube

4th

343=7^3

p^6 = (p^2) ^3

q^21 = (q^7) ^3

r^6 = (r^2) ^3

343p^6q^21r^6 = (7p^2q^7r^2) ^3

answer is last one is perfect cube