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ex.10 please!!! dau 10 puncte+coroana.

Ex10 Please Dau 10 Punctecoroana class=

Răspuns :

a+b=13          a=13-b
4xa+3xb=46     4x(13-b)+3xb=46    52-4b+3b=46  b=6
a=13-6=7
axbx10=6x7x10=420
rezolvare

4×a=a+3×a
a+3×a+3×b=46
a+3×(a+b)=46
a+3×13=46
a+39=46
a=46-39
a=7
7+b=13
b=13-7
b=6
a×b×10=?
7×6×10=42×10=420
9×7+10×6=63+60=123
6×6+□=145
□=145-36
□=109