Question

a) -2 (x+6)+6 (x-10)=8

b) ( x-12)-15=(20-7) - (18-x)

c)2(5+3x)+x=31

d) -x (x+7) ( x-4) =0

e) x-96 = (443 - x) - 15

Answer 1

a) -2 (x+6)+6 (x-10)=8

-2.x + (-2).6 + 6.x - 6.10 = 8

-2x + (-12) + 6x - 60 = 8

-2x + 6x + [60 + (-12)] = 8

4x + 48 = 8

4x = 8 - 48

4x = -40

x = -40 : 4

x = -10

vậy_____

b) ( x-12)-15=(20-7) - (18-x)

x - 12 - 15 = 13 - 18 + x

x - 27 = -5 + x

x - x = -5 + 27

0x = 22

x = 22 : 0

=> x ∈ ∅

c)2(5+3x)+x=31

2.5 + 2.3x + x = 31

10 + 6x + x = 31

6x + x = 31 - 10

7x = 21

x = 21 : 7

x = 3

vậy_____

d) -x (x+7) ( x-4) =0

=> -x = 0 hoặc x+ 7 = 0 hoặc x - 4 = 0

=> x = 0 hoặc x = 0 - 7 hoặc x = 0 + 4

=> x = 0 hoặc x = -7 hoặc x = 4

vậy_____

e) x-96 = (443 - x) - 15

x - 96 = 443 - x - 15

x - 96 = (443 - 15) - x

x - 96 = 428 - x

x + x = 428 + 96

2x  = 524

x = 524 : 2

x = 262

vậy_____