2 x 4 = 8 

k mk mk k lại 

1+2+3+4+1+2+3+4

=(1+2+3+4)+(1+2+3+4)

=10+10

=10x2

=20

Chúc bạn học giỏi nha!!!!

K cho mik với nhé 

bé khờ ơi mình chịu chết với cái phép của cậu luôn đó

nam 1441

45525

Xin lỗi nhé

\(24-3x=9\)

\(3x=24-9\)

\(3x=15\)

\(x=15:3\)

\(x=5\)

help me

Bài 1:

a)

\(\left(x-2\right)-15=65\)

\(x-2\) \(=65+15\)

\(x-2\) \(=\) \(80\)

\(x\) \(=80+2\)

\(x\) \(=82\)

b)

\(115-2\cdot\left(x-3\right)=35\)

\(2\cdot\left(x-3\right)=115-35\)

\(2\cdot\left(x-3\right)=80\)

\(x-3=80:2\)

\(x-3=40\)

\(x\) \(=40+3\)

\(x\) \(=43\)

c)

\(35+2\cdot\left(x-3\right)=65\)

\(2\cdot\left(x-3\right)=65-35\)

\(2\cdot\left(x-3\right)=30\)

\(x-3=30:2\)

\(x-3=15\)

\(x\) \(=15+3\)

\(x\) \(=18\)

d)

\(3\cdot\left(x-5\right)-16=11\)

\(3\cdot\left(x-5\right)\) \(=11+16\)

\(3\cdot\left(x-5\right)\) \(=27\)

\(x-5\) \(=27:3\)

\(x-5\) \(=9\)

\(x\) \(=9+5\)

\(x\) \(=14\)

Bài 2

a)

\(2^x-1=31\)

\(2^x\) \(=31+1\)

\(2^x\) \(=32\)

\(2^x\) \(=2^5\)

⇒ \(x=5\)

b)

\(x^3-1=26\)

\(x^3\) \(=26+1\)

\(x^3\) \(=27\)

\(x^3\) \(=3^3\)

⇒ \(x=3\)

c)

\(6^{x-1}+1=37\)

\(6^{x-1}\) \(=37-1\)

\(6^{x-1}\) \(=36\)

\(6^{x-1}\) \(=6^2\)

➞ \(x-1=2\)

\(x\) \(=2+1\)

\(x\) \(=3\)

d)

\(\left(x+2\right)^3-15^0=215\)

\(\left(x+2\right)^3-1=215\)

\(\left(x+2\right)^3=215+1\)

\(\left(x+2\right)^3=216\)

\(\left(x+2\right)^3=6^3\)

➞ \(x+2=6\)

\(x=6-2\)

\(x=4\)

e)

\(2\cdot\left(x-9\right)^2=2\)

\(\left(x-9\right)^2=2:2\)

\(\left(x-9\right)^2=1\)

\(\left(x-9\right)^2=1^2\)

➞ \(x-9=1\)

\(x=9+1\)

\(x=10\)

g)

\(3\cdot\left(x-5\right)^3=51\)

Câu hỏi này sai nhé bạn

Bảng nhân 9:

9 x 1 = 9

9 x 2 = 18

9 x 3 = 27

9 x 4 = 36

9 x 5 = 45

9 x 6 = 54

9 x 7 = 63

9 x 8 = 72

9 x 9 = 81

9 x 10 = 90