a) \(4x+12:3=40\)

\(4x+4=40\)

\(4x=40-4\)

\(4x=36\)

\(x=36:4\)

\(x=9\)

b) \(2^{x+7}+2017^0=65\)

\(2^{x+7}+1=65\)

\(2^{x+7}=65-1\)

\(2^{x+7}=64\)

\(2^{x+7}=2^6\)

\(x+7=6\)

\(x=6-7\)

\(x=-1\)

Đáp án cần chọn là: D

Lời giải chi tiết:

Đúng là đa thức 1 biến x

d:=145-37-55-263

=90-300

=-210

651​<531​+631​+731​+…+202331​<40

165<153+163<153+163+173+…+120233<153+163+173+…+120233+…+120233651​<531​+631​<531​+631​+731​+…+202331​<531​+631​+731​+…+202331​+…+202331​

165<153+163<153+163+173<153+163+173+…+120233651​<531​+631​<531​+631​+731​<531​+631​+731​+…+202331​

Chúng ta có thể thấy rằng:

173+…+120233<165×(20233−73+1)731​+…+202331​<651​×(20233−73+1)

173+…+120233<165×20161731​+…+202331​<651​×20161

173+…+120233<165×311731​+…+202331​<651​×311

173+…+120233<31165731​+…+202331​<65311​

Từ đó, chúng ta có thể kết luận rằng:

165<153+163+173+…+120233<31165651​<531​+631​+731​+…+202331​<65311​

Vì 31165≈4.7846<4065311​≈4.7846<40

=) đpcm

a) \(8x+56:14=60\)

\(\Rightarrow8x+4=60\)

\(\Rightarrow8x=56\)

\(\Rightarrow x=\dfrac{56}{8}\)

\(\Rightarrow x=7\)

b) Mình làm rồi nhé !

c) \(41-2^{x+1}=9\)

\(\Rightarrow2^{x+1}=41-9\)

\(\Rightarrow2^{x+1}=32\)

\(\Rightarrow2^{x+1}=2^5\)

\(\Rightarrow x+1=5\)

\(\Rightarrow x=4\)

d) \(3^{2x-4}-x^0=8\)

\(\Rightarrow3^{2x-4}-1=8\)

\(\Rightarrow3^{2x-4}=9\)

\(\Rightarrow3^{2x-4}=3^2\)

\(\Rightarrow2x-4=2\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=3\)

g) \(65-4^{x+2}=2014^0\)

\(\Rightarrow65-4^{x+2}=1\)

\(\Rightarrow4^{x+2}=64\)

\(\Rightarrow4^{x+2}=4^3\)

\(\Rightarrow x+2=3\)

\(\Rightarrow x=1\)

i) \(120+2\left(4x-17\right)=214\)

\(\Rightarrow2\left(4x-17\right)=214-120\)

\(\Rightarrow2\left(4x-17\right)=94\)

\(\Rightarrow4x-17=47\)

\(\Rightarrow4x=47+17\)

\(\Rightarrow4x=64\)

\(\Rightarrow x=16\)

a: \(8x+56:14=60\)

=>8x+4=60

=>8x=60-4=56

=>x=56/8=7

b: \(5^{2x-3}-2\cdot5^2=5^2\cdot3\)

=>\(5^{2x-3}=5^2\cdot3+2\cdot5^2=5^3\)

=>2x-3=3

=>2x=6

=>x=3

c: \(41-2^{x+1}=9\)

=>\(2^{x+1}=41-9=32\)

=>x+1=5

=>x=4

d: \(3^{2x-4}-x^0=8\)

=>\(3^{2x-4}-1=8\)

=>\(3^{2x-4}=8+1=9\)

=>2x-4=2

=>2x=6

=>x=3

g: \(65-4^{x+2}=2014^0\)

=>\(65-4^{x+2}=1\)

=>\(4^{x+2}=65-1=64\)

=>x+2=3

=>x=1

i: 120+2(4x-17)=214

=>2(4x-17)=214-120=94

=>4x-17=94/2=47

=>4x=64

=>\(x=\dfrac{64}{4}=16\)

1: =>\(5^{2x-3}=5^2\cdot3+5^2\cdot2=5^2\cdot5=5^3\)

=>2x-3=3

=>2x=6

=>x=3

2: \(41-2^{x+1}=9\)

=>\(2^{x+1}=32\)

=>x+1=5

=>x=4

3: =>\(4^{x+2}=65-1=64\)

=>x+2=3

=>x=1

\(5^{2x-3}-2.5^2=5^2.3\\ 5^{2x-3}=5^2.3+5^2.2\\ 5^{2x-3}=5^2.\left(3+2\right)\\ 5^{2x-3}=5^2.5\\ 5^{2x-3}=5^3\\ \Rightarrow2x-3=3\\ 2x=3+3\\ 2x=6\\ x=\dfrac{6}{2}\\ Vậy:x=3\)

\(41-2^{x+1}=9\\ 2^{x+1}=41-9\\ 2^{x+1}=32=2^5\\ \Rightarrow x+1=5\\ \Leftrightarrow x=5-1=4\\ ---\\ 65-4^{x+2}=2014^0\\ 65-4^{x+2}=1\\ 4^{x+2}=65-1\\ 4^{x+2}=64=4^3\\ \Rightarrow x+2=3\\ Vậy:x=1\)

4^(4x-5)-1=65

4^(4x-5)=65-1

4^(4x-5)=64

4^(4x-5)=4^3 (vì 4>0)

=>4x-5=3

=>4x=3+5

=>4x=8

=>x=8:4

=>x=2

Vậy x=2