Question

stiind ca:
9a+12b+7=28, află 3a+4b
4a+10b-3=27, afla 2a+5b
7a+14b+21=105, află 3a+6b
5a+15b+10z=30, afla 3a+9b+6z
6a-12b-5=67, află 13+5a-10b
dau coroana și 5 stele inima si puncte ogramada va rog ziceți ​

Answer 1

a) 9a+12b+7=28 |-7

9a+12b=21 |÷3

3a+4b=7

b) 4a+10b-3=27 |+3

4a+10b=30 |÷2

2a+5b=15

c) 7a+14b+21=105 |-21

7a+14b=84 |÷7

a+2b=12 |×3

3a+6b=36

d) 5a+15b+10z=30 |÷5

a+3b+2z=6 |×3

3a+9b+6z=18

e) 6a-12b-5=67 |+5

6a-12b=72 |÷6

a-2b=12 |×5

5a-10b=60 |+13

5a-10b+13=73

Answer 2

•9a+12b+7=28|-7
9a+12b=21/ dam factor comun 3
3(3a+4b)=7=> 3a+4b= 7/3
•4a+10b-3=27/+3
4a+10b=30( dam factor comun 2)
2(2a+5b)=15=> 2a+5b=15/2
•7a+14b+21=105/-21
7a+14b=84 ( dam factor comun 7)
7(a+2b)=6=> a+2b=6/7=> 3a+6b=6/7 amplificat cu 3=> 3a+6b= 18/21
•5a+15b+10z=30 (dam factor comun 5)
5(a+3b+2z)=15=> a+3b+2z=15/2=> 3a+9b+6z= 15/2 amplificat cu 3=> 3a+9b+6z= 45/6
•6a-12b-5=67/+5
6a-12b= 72 (dam factor comun 6)
6(a-2b)=12=> a-2b=12/6=2
=>a-2b=2 => 5a-10b=2* 5= 10
=> 13+5a-10b= 13+10=23