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a)Stiind ca x+2•y=24 si x+y=19, determinati y.
B) stiind ca 3•x+2•y=17 si 2•x+2•y= 13 determinati x
c) stiind ca x+2•y+z=17 si x+y=10 detrrminati y+z


Răspuns :

x+2y=24, adica x+y+y=24
stim ca x+y=19, deci 19+y=24, y=24-19=5

3•x+2•y=17,x+2•x+2•y=17, adica x+13=17, x=17-13=4


x+2•y+z=17, x+y+y+z=17, 10+y+z=17, deci y+z=17-10=7