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8Si9


8Si9 class=

Răspuns :

[tex]8)x - y = 12[/tex]

[tex]z = 10[/tex]

[tex]xz - yz = z(x - y) = 10 \times 12 = 120[/tex]

[tex]9)b + c = 14[/tex]

[tex]ab + ac = 420[/tex]

[tex]a(b + c) = 420[/tex]

[tex]14a = 420 [/tex]

[tex]a = 420 \div 14[/tex]

[tex]a = 30[/tex]

8. x-y=12, z=10 ⇒ xz-yz=z(x-y)=10x12= 120

9. ab+ac=420, b+c=14 ⇒ a(b+c)=420 ; inlocuim b+c=14, ax14=420 ⇒a=420:14= 30