Question

99 puncte (va rog) .................. 10 , 11 , 12

Answer 1

10)Aducem termenii din paranteza la acelasi numitor :36

$( \frac{5*3}{12*3} + \frac{7*2}{18*2} ): \frac{29}{100} = \frac{15+14}{36} * \frac{100}{29} - \frac{7}{9} =$

[tex] \frac{29}{36}* \frac{100}{29} - \frac{7}{9} =
simplificam 29 cu 29 prin 29  si 36 cu 100 prin  4 si obtinem
[/tex]$\frac{1}{9} * \frac{25}{1} - \frac{7}{9} =$

$\frac{25}{9} - \frac{7}{9} =$

$\frac{18}{9} =2$

11)7a2b div cu 45⇒ 7a2b div cu 5 ⇒b∈{0,5}
                             7a2b div cu 9 ⇒(7+a+2+b) div cu 9
pt b=0⇒7a20 div cu 9⇒a=9⇒7920
   b=5⇒7a25 div cu 9⇒a=4⇒7425

12)x+y+z=20
$\frac{x}{2} = \frac{y}{3} = \frac{z}{5}= \frac{x+y+z}{2+3+5} = \frac{20}{10}=2$
$\frac{x}{2}=2$⇒x=2*2⇒x=4

$\frac{y}{3} =2$⇒y=2*3⇒y=6

$\frac{z}{5}=2$⇒z=2*5⇒z=10