x=5; y=0

x=2 chứ

2) \(A=3+3^2+3^3+...+3^{12}\)

\(3A=3^2+3^3+3^4+...+3^{13}\)

\(3A-A=\left(3^2+3^3+3^4+...+3^{13}\right)-\left(3+3^2+3^3+...+3^{12}\right)\)

\(2A=3^{13}-3\)

\(A=\frac{3^{13}-3}{2}\)

Suy ra \(3^{13}=3^x\Leftrightarrow x=13\).

\(x+2016=13+2016=2029\)

3) \(A=5.4^{15}.9^9-4.3^{20}.8^9=5.2^{30}.3^{18}-3^{20}.2^{29}=2^{29}.3^{18}\left(5.2-3^2\right)=2^{29}.3^{18}\)

\(B=5.2^9.6^{19}-7.2^{29}.27^6=5.2^{28}.3^{19}-7.2^{29}.3^{18}=2^{28}.3^{18}\left(5.3-7.2\right)=2^{28}.3^{18}\)

\(\frac{A}{B}=\frac{2^{29}.3^{18}}{2^{28}.3^{18}}=2\)

2) A = 3 + 3^2 + 3^3 + ... + 3^12 = 3^x-3/2 

3A = 3^2 + 3^3 + ... + 3^13 . 2A = 3A - A = 3^13 - 3 => x =13. Vậy x + 2016 = 2029

3) A= 5 . 2^30 . 3^18 - 3^20 . 2^29 = 2^29 . 3^18 . (5.2 - 3^2) = 2^29 . 3^18

B = 5. 2^28 . 3^19 - 7.2^29. 3^18 = 2^28.3^18 . ( 5.3 - 7.2 ) = 2^28.3^18

A/B = 2^29 . 3^18 / 2^28 . 3^18 = 2

có ai lm đc ko

92−2x=2.42−3.4+120:1592-2x=2.42-3.4+120:15

⇔92−2x=2.16−12+8⇔92-2x=2.16-12+8

⇔92−2x=32−12+8⇔92-2x=32-12+8

⇔92−2x=20+8⇔92-2x=20+8

⇔92−2x=28⇔92-2x=28

⇔2x=92−28⇔2x=92-28

⇔2x=64⇔2x=64

⇔x=64:2⇔x=64:2

⇔x=32⇔x=32

Vậy ,x=32.

khó té

Trả lời :
Đáp số : a = 7

# Hok tốt !

nè ai học kb nha 

thành phố nào

kb đc ko

t hải dương

lê quý đôn

lớp 6

92-2x=2.4 mu 2-3.4+120:15

Đáp án:

x=32x=32

Trình bày lời giải:

92−2x=2.42−3.4+120:1592-2x=2.42-3.4+120:15
⇒92−2x=2.16−12+8⇒92-2x=2.16-12+8
⇒92−2x=32−12+8⇒92-2x=32-12+8
⇒92−2x=20+8⇒92-2x=20+8
⇒92−2x=28⇒92-2x=28
⇒2x=92−28⇒2x=92-28
⇒2x=64⇒2x=64
⇒x=64:2⇒x=64:2
⇒x=32⇒x=32
Vậy x=32x=32