a) radical (2^8 * 7^2) = 2^4 * 7 = 16 * 7 = 112
b) radical(3^52 * 11^40) = 3^26 * 11^20
c) radical (64^2-63^2+4^2+1^2) = radical(4096-3969+16+1) = radical 144 = radical(2^4*3^2) = 2^2*3 = 12
d) radical(9^2-6^2+2^2) = radical(81-36+4) = radical49 = radical(7^2) = 7