Question

punctul 6 abcd tot tot tot

Answer 1

a) ac+bc=168
c=7

a+b=?

ac+bc= c (b+c)
c (b+c)=168
7 (b+c)=168
b+c= 168:7
b+c= 24

b) ac- bc=540
a-b=12
c=?

ac-bc= c (a-b)
c (a-b)=540
c×12=540
c=540:12
c=45

c) a+b=17
c=12
ac+bc=?

ac+bc= c (a+b)
c (a+b) = 12×17
ac+bc=204


d) a-b=34
c=16
ac-bc=?

ac-bc= c (a-b)
c (a-b)= 16×34
ac-bc=544



Sper ca te-am ajutat!!! Si eu am facut exercitii asemanatoare cu profesoara mea!!! BAFTA!!!

Answer 2

$\displaystyle a).ac+bc=168;~c=7;~a+b=? \\ ac+bc=168 \Rightarrow c(a+b)=168 \Rightarrow 7(a+b)=168 \Rightarrow \\ \Rightarrow a+b= \frac{168}{7} \Rightarrow \boxed{a+b=24} \\ b).ac-bc=540;~a-b=12;~c=? \\ ac-bc=540 \Rightarrow c(a-b)=540 \Rightarrow 12c=540 \Rightarrow c= \frac{540}{12} \Rightarrow\boxed{c=45}\\c).a+b=17;~c=12,~ac+bc=? \\ ac+bc=c(a+b) \Rightarrow ac+bc=12 \cdot17 \Rightarrow \boxed{ac+bc=204}\\ d).a-b=34,~c=16,~ac-bc=?\\ac-bc=c(a-b) \Rightarrow ac-bc=16 \cdot 34 \Rightarrow \boxed{ac-bc=544}$