\(Cho\)\(P\)\(v\text{à}\)\(P+14\)\(l\text{à}\)\(hai\)\(s\text{ố}\)\(nguy\text{ê}n\)\(t\text{ố}\)

\(CMR:\)\(P+7\)\(l\text{à}\)\(h\text{ợp}\)\(s\text{ố}\)

\(Cho\)\(c\text{ác}\)\(s\text{ố}\)\(a,b,c,d,p\)\(l\text{à}\)\(c\text{ác}\)\(s\text{ố}\)\(nguy\text{ê}n\)\(t\text{ố}\)\(th\text{ỏa}\)\(m\text{ãn:}\)\(p=a+b=c-d.\)\(T\text{ìm}\)\(c\text{ác}\)\(s\text{ố}\)\(a,b,c,d\)\(v\text{à}\)\(p\)

 1) Vẽ góc \(\widehat{\text{xOy}}\) = 89^o

   a) Vẽ các tia Om, On nằm giữa hai tia Ox, Oy sao cho \(\widehat{\text{mOn}}\) = 78^o. Tính \(\widehat{mOn}\) + \(\widehat{\text{yOn}}\).

   b) Vẽ các tia Om^', On^' nằm giữa hai tia Ox, Oy sao cho \(\widehat{\text{xOm'}}\) + \(\widehat{\text{yOn'}}\) = 123^o. Tính góc \(\widehat{\text{m'On'}}\)

\(Cho\)\(P=5+5^2+5^3+5^4+...+5^{102}\)

\(Ch\text{ứng}\)\(minh\)\(r\text{ằng:}\)\(P\)\(l\text{à}\)\(b\text{ội}\)\(c\text{ủa}\)\(6\)\(v\text{à}\)\(31\)

1) Vẽ góc \(\widehat{\text{xOy}}\) = 89^o

a) Vẽ các tia Om, On nằm giữa hai tia Ox, Oy sao cho \(\widehat{\text{mOn}}\) = 78^o. Tính \(\widehat{mOn}\) + \(\widehat{\text{yOn}}\).

b) Vẽ các tia Om^', On^' nằm giữa hai tia Ox, Oy sao cho \(\widehat{\text{xOm'}}\) + \(\widehat{\text{yOn'}}\) = 123^o. Tính góc \(\widehat{\text{m'On'}}\)

\(\text{Vẽ hai}\) \(\widehat{AOB}\)\(\text{và}\)\(\widehat{BOC}\)\(\text{là hai góc kề bù.Vẽ tia OD là tia phân giác của}\)\(\widehat{AOB}\)\(.\)\(\text{OE là tia phân giác của}\) \(\widehat{BOC}\)\(\text{Tính}\)\(\widehat{BOE}\)