BT: Tim x biet
a, / 2 + x / + / x - 7 / = 3 (bat dang thuc)
b, / 13 - x / + / 6 + x / =7 (bat dang thuc)
c, / 8 + x / + / x - 5 / = 17 ( lap bang xet dau)
d, / 16 - x / + / 7 + x / = 22
e, / 8 + x / + / x - 8 / = 10
( "/" la dau gia tri tuyet doi nha )