Răspuns :
Inlocuim pe rand pe x=2/7 in ecuatiile A. ... D.
A. 2*2/7-7=0 ⇔ 4/7 - 7 = 0 (F)
B. 7*2/7+3=5 ⇔ 2+3 = 5 (A)
C. 7*2/7+2=0 ⇔ 2+2 = 0 (F)
D. 9*2/7 -3=2*2/7 ⇔ 18/7 -3=4/7 | *7 ⇔ 18-21 = 4 (F)
A. 2*2/7-7=0 ⇔ 4/7 - 7 = 0 (F)
B. 7*2/7+3=5 ⇔ 2+3 = 5 (A)
C. 7*2/7+2=0 ⇔ 2+2 = 0 (F)
D. 9*2/7 -3=2*2/7 ⇔ 18/7 -3=4/7 | *7 ⇔ 18-21 = 4 (F)