(9-10)+(11-12)+(13-14)+(15-16)

= (-1) + (-1)+( -1)+ (-1)

= -4

=645-(-38)+(-45)

=645+38+(-45)

=683+(-45)

=638

638.

\(2^x+2^{x+1}+2^{x+2}=56\)

\(2^x\left(1+2+2^2\right)=56\)

\(2^x\cdot7=56\)

\(2^x=8\)

\(x=3\)

sàm vãi

a)   x + 118 = 218

x = 218 – 118

x = 100

b)   18 – x = -17

X = 18 – (-17)

X = 35

c)    (-18) – x = -17

X = (-18) – (-17)

X = -1

d)124 + (118 – x) = 217

118 – x = 93

X = 118 – 93

X = 25

e) (3x – 6).3 = 3⁴

(3x – 6).3 = 81

3x – 6 = 27

3x = 33

ð X = 11

g) 23.(42 – x) = 46

42 – x = 2

ð X = 40

h) 84 – (3x + 8) = 34

3x + 8 = 84 – 34

3x + 8 = 50

3x = 50 – 8

3x = 42

X = 42 : 3

ð X = 14

i)               3.(2x + 1) – 19 = 14

3.(2x + 1) = 14 + 19

3.(2x + 1) = 33

2x + 1 = 33 : 3

2x + 1 = 11

2x = 11 – 1

2x = 10

X = 10 : 2

ð X = 5

k) 6x – 302 = 2³.5

6x – 302 = 40

6x = 40 + 302

6x = 342

X = 342 : 6

ð X = 57

m) (x – 1)² = 81

(x – 1)² = 9²

ð X – 1 = 9

ð X = 9 + 1

ð X = 10

n) 2^x+1 – 5 = 27

2^x+1 = 27 + 5

2^x+1 = 32

2^x+1 = 2⁵

ð X = 4

a. 24 x (-125 + 225)

= 24 x 100

=2400

b. -125 x ( 24 -36 )

= -125 x -12

= 1500

c. 512 x (2 -128+128)

= 512 x 2

= 1024

d. \([4.25].\left[\left(-2\right).\left(-5\right)\right].\left[125.\left(-8\right)\right]\)

= 100.10.(-1000)

= -1000000

a. 24 x (-125 + 225)

= 24 x 100

=2400

b. -125 x ( 24 -36 )

= -125 x -12

= 1500

c. 512 x (2 -128+128)

= 512 x 2

= 1024

d. $[4.25].\left[\left(-2\right).\left(-5\right)\right].\left[125.\left(-8\right)\right]$

= 100.10.(-1000)

= -1000000

Vì a lớn nhất mà 480 ⋮ a; 720 ⋮ a ⇒ a = ƯCLN ( 480; 720 )

Ta có 480 = 2⁵ . 3 . 5              720 = 2⁴ . 3² . 5

⇒ a = ƯCLN ( 480; 720 ) = 2⁴ . 3 . 5 = 240

Vậy a = 240

|x - 5|  + 19 = 20

|x -5 |          = 20 - 19

| x - 5|         =   1

\(\left[{}\begin{matrix}x-5=1\\x-5=-1\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=6\\x=4\end{matrix}\right.\)

\(x\in\) { 4; 6}

\(|x-5|=1\)

\(\left\{{}\begin{matrix}x-5=1\\x-5=-1\end{matrix}\right.\)

\(\left\{{}\begin{matrix}x=6\\x=4\end{matrix}\right.\)