Tìm x biết

5. Tìm x biết:

a) 456 + (x - 357) = 1362; b) (2345 - x) - 183 = 2014;

c) (x - 2002). 2006 = 0; d) 480 + 45. 4 = (x + 125) : 5 + 260;

e) 2005. (x - 2006) = 2005; g) [(x + 50) . 50 - 50] : 50 = 50.

Bài làm:

a) 456 + (x - 357) = 1362

x - 357 = 1362 - 456

x = 1362 - 456 + 357

x = 1263

b) (2345 - x) - 183 = 2014

2345 - x = 2014 + 183

x = 2345 - 2014 -183

x = 148

c) (x - 2002). 2006 = 0

x - 2002 = 0

x = 2002

d) 480 + 45. 4 = (x + 125) : 5 + 260

(x + 125) : 5 = 660 - 260

(x + 125) : 5 = 400

x + 125 = 2000

x = 1875

e) 2005. (x - 2006) = 2005

x - 2006 = 1

x = 2007

g) [(x + 50) . 50 - 50] : 50 = 50

(x + 50). 50 - 50 = 2500

(x + 50). 50 = 2550

x + 50 = 51

x = 1