4. Let H be a subgroup of R under addition. Let K = {2ª : a € H}. Prove that K is a subgroup of R' under multiplication. 5. Let R' be the group of nonzero real numbers under multiplication and let H =...

Extracted text: 4. Let H be a subgroup of R under addition. Let K = {2ª : a € H}. Prove that K is a subgroup of R' under multiplication. 5. Let R' be the group of nonzero real numbers under multiplication and let H = {x € R' : x² is rational } Prove that H is a subgroup of R'. 6. In the group Z, find or describe (8,14).