Răspuns:
1a) 2+4+6+...+26=2(1+2+3+...13)=2*13*14/2=13*14=182
b)[tex][(3^{3})^{2}:3^{6} +(2^{4} *2^{5}):2^{6}]*9+(35^{2})^{a} =\\ (3^{6}:3^{6}+2^{7}:2^{6})*9+(35^{2})^{a} = \\(1+2)*9+(35^{2})^{a}=27+(35^{2})^{a}[/tex]
c) [tex](1\frac{1}{26} *\frac{13}{45} +1\frac{1}{21}:1\frac{27}{28})*2\frac{2}{15} =\\=(\frac{27}{26} *\frac{13}{45} +\frac{22}{21}:\frac{55}{28} )*\frac{32}{15} =\\=(\frac{3}{2} *\frac{1}{5} +\frac{22}{21}*\frac{28}{55} )*\frac{32}{15} =\\\\=(\frac{3}{10} +\frac{2}{3}*\frac{4}{5} )*\frac{32}{15} = \\=(\frac{3}{10} +\frac{8}{15})*\frac{32}{15} =\\=(\frac{9}{30} +\frac{16}{30})*\frac{32}{15} =\frac{25}{30}*\frac{32}{15} = \\ \frac{25}{30}*\frac{32}{15} =\\\frac{1}{3}*\frac{16}{3} =\\\frac{16}{9}[/tex]
III. 1. 4c+7s=71
5c+3s=37 ⇒c=[tex]\frac{37-3s}{5}[/tex]
4[tex]\frac{37-3s}{5}[/tex]+7s=71 / *5
4(37-3s)+35s=355
148-12s+35s=355
23s=355-148
23s=207⇒s=7
4c+7*7=71
4c=71-49
4c=22 ⇒ c=2,50
2. (a+b+c):3=14.59
(a+b+7.25):3=14.59 / *3
a+b=14.59*3
a+b=43.77 ⇒(a+b)/2=21.885
3. L=36 ; l=3*L:4
l=3*36:4=27
P=2(L+l)=2(36+27)=2*63=126 cm
A=L*l=36*27=972[tex]cm^{2}[/tex]
Explicație pas cu pas: