b. 2(x – 1) – 5(x + 2) = – 10 c. 2(x – 5) – 3(x + 7) = 14 d. 5(x – 6) – 2(x + 3) = 12 e.-7(5 – x) – 2(x – 10) = 15 f. 3(x – 4) – (8 – x) = 12

0 bình luận về “b. 2(x – 1) – 5(x + 2) = – 10 c. 2(x – 5) – 3(x + 7) = 14 d. 5(x – 6) – 2(x + 3) = 12 e.-7(5 – x) – 2(x – 10) = 15 f. 3(x – 4) – (8 – x) = 12”

1. b)2(x – 1) – 5(x + 2) = – 10

   =>2x-2-5x-10=-10

   =>-3x=-10+10+2

   =>-3x=2

   =>x=-2/3

   c)2(x – 5) – 3(x + 7) = 14

   => 2x-10-3x-21=14

   =>-x=14+21+10=45

   => x=-45

   d)5(x – 6) – 2(x + 3) = 12

   => 5x-30-2x-6=12

   =>3x=12+6+30=48

   => x=16

   e, -7(5 – x) – 2(x – 10) = 15

   => -35 + 7x – 2x + 20 = 15

   =>(-35 + 20) + (7x – 2x) = 15

   => -15 + 5x = 15

   => 5x = 15 – (-15)

   =>5x = 15 + 15

   =>5x = 30

   =>x = 30 : 5

   =>x = 6

   f. 3(x – 4) – (8 – x) = 12

   =>3x-12-8+x=12

   =>4x=12+12+8=32

   =>x=8

   hoctot

   @huyenthaikhanh098

    

   Trả lời

2. b, 2(x – 1) – 5(x + 2) = -10

   ⇒ 2x – 2 – 5x – 10 = -10

   ⇒ (2x – 5x) – 2 = 0

   ⇒  (-3)x = 2

   ⇒     x = 2 : (-3)

   ⇒     x = $\frac{-2}{3}$ 

   c, 2(x – 5) – 3(x + 7) = 14

   ⇒ 2x – 10 – 3x – 21 = 14

   ⇒ (2x – 3x) – (10 + 21) = 14

   ⇒   (-1)x – 31 = 14

   ⇒   (-1)x = 14 + 31

   ⇒  (-1)x =  45

   ⇒       x = 45 : (-1)

   ⇒       x = -45

   d, 5(x – 6) – 2(x + 3) = 12

   ⇒ 5x – 30 – 2x – 6 = 12

   ⇒ (5x – 2x) – (30 + 6) = 12

   ⇒    3x – 36 = 12

   ⇒     3x = 12 + 36

   ⇒     3x = 48

   ⇒       x = 48 : 3

   ⇒       x = 16

   e, -7(5 – x) – 2(x – 10) = 15

   ⇒ -35 + 7x – 2x + 20 = 15

   ⇒ (-35 + 20) + (7x – 2x) = 15

   ⇒  -15 + 5x = 15

   ⇒            5x = 15 – (-15)

   ⇒            5x = 15 + 15

   ⇒            5x = 30

   ⇒              x = 30 : 5

   ⇒              x = 6

   f, 3(x – 4) – (8 – x) = 12

   ⇒ 3x – 12 – 8 + x = 12

   ⇒ (3x + x) – (12 + 8) = 12

   ⇒   4x – 20 = 12

   ⇒          4x = 12 + 20

   ⇒          4x = 32

   ⇒            x = 32 : 4

   ⇒            x = 8

    

   Trả lời