can someone help me with this questuon please its fundamnetal to the topic and preventing me understand the topic!!

Thanks

Edgar

if G is a group and x is an element of G we define the order ord(x) of x by

ord(x) = min {r > or equal to 1 : x^r=1}

if f:G maps to His an injective group homomorphism show that for each x

ord (f(x)) = ord (x)