a: x+3/7=7/6

=>x=7/6-3/7=49/42-18/42=31/42

b: 12/7-x=5/14

=>x=12/7-5/14=24/14-5/14=19/14

a.\(x+\dfrac{3}{7}=\dfrac{7}{6}\)

\(x=\dfrac{7}{6}-\dfrac{3}{7}\)

\(x=\dfrac{49-18}{42}=\dfrac{31}{42}\)

b.\(\dfrac{12}{7}-x=\dfrac{5}{14}\)

\(x=\dfrac{12}{7}-\dfrac{5}{14}\)

\(x=\dfrac{24-5}{14}=\dfrac{19}{14}\)

a \(x=\dfrac{7}{6}-\dfrac{3}{7}\)

\(x=\dfrac{40}{21}\)

b \(x=\dfrac{12}{7}-\dfrac{5}{14}\)

\(x=\dfrac{19}{14}\)

a x 3 + a x 2 + a = 612

a x (3 + 2 + 1) = 612

a x 6 = 612

a = 612 : 6

a = 102

a x 3+a x 2+a=612

ax(3+2+1)=612

a x 6=612

a     =102

ax3+ax2+a=612

ax3+ax2+ax1=612

ax(3+2+1)=612

ax6=612

a=612:6

a=102

\(\left\{240-\left[76-\left(9-3\right)^2\right]\right\}:50\)

\(=\left[240-\left(76-6^2\right)\right]:50\)

\(=\left[240-\left(76-36\right)\right]:50\)

\(=\left(240-40\right):50\)

\(=200:50\)

\(=4\)

_______________

\(\dfrac{4^6\cdot3^4\cdot9^5}{6^{12}}\)

\(=\dfrac{2^{12}\cdot3^4\cdot3^{10}}{6^{12}}\)

\(=\dfrac{2^{12}\cdot3^{14}}{2^{12}\cdot3^{12}}\)

\(=\dfrac{1\cdot3^2}{1\cdot1}\)

\(=3^2\)

\(=9\)

5^x+3 -13=612

5^x+3 =612+13

5^x+3 =625

5^x+3 =5⁴

=>x+3=4

x=4-3

x=1

5^x+3-13=612

=> 5^x+3=612+13

=> 5^x+3=625

=> 5^x+3=5⁴

=> x+3=4

=> x=4-3

=> x=1

a) x = 1/2

b) x = 70/153

c) x = dư ( có sai đề ko bạn )

~Ủng hộ mk nha các bạn~

ừ mình nhầm câu c) là X * 306 = 36108 + 612 

1121

9 nha ban

chuc ban hoc tot

123 + 143 + 621 + 243 = 1121

12 - 3 = 9

chúc bn hok tốt

123+143+612+243=1121

12-3=9

hok tốt

ủng hộ mk nha ~^_^~

2 nha Lương Ngọc Linh

\(Đápsố:2\)

612/1020:3/10

=612/1020X10/3

=6120/3060=2

Tính 12 – 3.

• Tách: 12 = 10 + 2.

• 10 – 3 = 7

• 7 + 2 = 9

• 12 – 3 = 9

Tính tương tự với các phép trừ còn lại ta có kết quả như sau:

12 – 3 = 9                12 – 4 = 8                  12 – 5 = 7                12 – 6 = 6

12 – 7 = 5                 12 – 8 = 4                  12 – 9 = 3               12 – 2 = 10