If |→a|=2, |→b|=3 and |2→a−→b|=5, then |2→a+→b| equals.

First find ||2→a||=2||→a||=4
Given that ||2→a−→b||²=||2→a||²+||→b||²−2(2→a⋅→b)=25
25=16+9−4(→a⋅→b)
25=25−4(→a⋅→b)
→a⋅→b=0
We have ||2→a+→b||²=||2→a||²+||→b||²+2(2→a⋅→b)=16+9=25
→||2→a+→b||=5