solve (a problem); answer (a question); unravel (a riddle) / comb; untangle (hair)

untie; unravel; undo (a fastening); unwrap / dispel (doubts); clear up (a matter)

to use / to employ / to make use of, to apply / to spend

mathematics (field of study)

君: second person personal pronoun, you

近似: approximation

欣士, 金二: a male given name

近似: to resemble closely

禁じる: to prohibit

金次郎: a male given name