va rog ajutatima la testul 2 plsssss
Răspunsuri la întrebare
1.
(2-6)³-(2³-6³)+√(15²-12²)
√(15²-12²)=√225-144=√81=9
(2-6)³=-4³= - 64
(2³-6³)=(8-216)=-208
- 64 - (-208) +9 = - 64 + 208 +9 = 153
2. stiind ca x/y=4/9 calculati (3x+y)/(5x+4y)
x/y=4/9 ⇒x=4y/9
3×(4y/9)+y]/[5×(4y/9)+4y]=[(4y+3y)/3[/[(20y/9+4y)]
=(7y/3)/3]/[56y/6]
=(7y/3)×(9/56y)
(3x+y)/(5x+4y)= 3/8
3.
6x/5y=0,48
0,48=48/100=24/50=15/25
6x/5y=12/25⇒ x =(12×5y)/(6×25)⇒x=2y/5
(11x-2y)/(9x+6y)=[(11×(2y/5)-2y]/[(9×2y/5)+6y)]
=(22y-10y)/5]/[{18y/5+6y}]
=(12y/5)/(48y/5)
(11x-2y)/(9x+6y)=1/4
4.
(4x+9)/(5y+6)=3/2 atunci x/y=?
2(4x+9)=3(5y+6)⇒8x+18=15y+18⇒8x=15y⇒
x/y=15/8
5.
[(6x-3y)/(4x+5y)]=3/16
16(6x-3y)=3((4x+5y)
96x-48y=12x+15y
84x=63y
x/y=9/12
x=9y/12
[5×(9y/12)+6y]/[10×(9y/12)-3y]=
[(45y+72y)/12]/[(90y-36y)/12]
=127y/54y
=127/54
6.
7(2x-1)-6(11-x)=3(x+4)
(14x - 7) - 66 + 6x = 3x +12
20x - 3x = 12 + 66 + 7
17x = 78 + 7
x = 85 / 17
c)
4(2x-3)+6(3x-2)=3(4x+3)-5
8x-24+18x-6=12x+9-5
26x-12x=4+36
14x=40
x=20/7=2 si 6/7