l) 7x-x = 521:519+3*22-70
<=> 6x = -1555/519
<=> x = -1555/3114
m) 7x – 2x = 617: 615 + 44 : 11
<=> 5x = 3077/615
<=> x = 3077/3075
n) 0 : x = 0
<=> x thuộc R
o) 3x = 9 <=> x = 3
p) 4x = 64 <=> x = 16
q) 2x = 16 <=> x = 8
r) 9x- 1 = 9 <=> x = 10/9
s) x^4 = 16 <=> x = { 2;-2 }
t) 2x : 25 = 1 <=> x 25/2