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15 tháng 7 2018

\(\left(3x-2^4\right)\cdot7=2\cdot7^2\)

\(\Leftrightarrow3x-2^4=2\cdot7^2:7\)

\(\Leftrightarrow3x-16=2\cdot7\)

\(\Leftrightarrow3x-16=14\)

\(\Leftrightarrow3x=14+16\)

\(\Leftrightarrow3x=30\)

\(\Leftrightarrow=30:3\)

\(\Leftrightarrow x=10\)

Vậy x=10

12 tháng 9 2018

a) \(\left(12x-4^3\right).8^3=4.8^4\)

\(12x-4^3=32\)

12x  = 96

x = 8

12 tháng 9 2018

b) \(\left(3x-2^4\right).7^3=2.7^4\)

3x - 24 = 14

3x = 30

x = 10

14 tháng 10 2018

Bo may la binh day k di hieu ashdbfgbgygygggydfsghuyfhdguuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu3

\(a.3x^2-50=142\)

\(3x^2=142+50\)

\(3x^2=192\)

\(x^2=192:3\)

\(x^2=64\)

\(\Rightarrow x=8\)

vậy: x=8.

\(b.3x^2=192\)

\(x^2=192:3\)

\(x^2=64\)

\(\Rightarrow x=8\)

Vậy: x=8.

\(c.4x^2=100\)

\(x^2=100:4\)

\(x^2=25\)

\(\Rightarrow x=5\)

vậy: x=5.

\(d.x^2+7=56\)

\(x^2=56-7\)

\(x^2=49\)

\(\Rightarrow x=7\)

Vậy: x=7.

<câu e bạn xem lại cho mk có phải sai đầu bài không nha,tại mk thấy kết quả là 21 nhưng mà không có cái nào bình phương =21 cả> 

 

 

 

 

29 tháng 9 2022

a.3x2−50=142

3x2=142+50

3x2=192

x2=192:3

x2=64

⇒x=8

vậy: x=8.

b.3x2=192

x2=192:3

x2=64

⇒x=8

Vậy: x=8.

c.4x2=100

x2=100:4

x2=25

27 tháng 8 2020

a) \(\frac{3}{7}-\frac{1}{7}x=\frac{2}{3}\)

=> \(\frac{1}{7}x=\frac{3}{7}-\frac{2}{3}=-\frac{5}{21}\)

=> \(x=-\frac{5}{21}:\frac{1}{7}=-\frac{5}{21}\cdot7=-\frac{5}{3}\)

b) \(3x^2-2=72\)=> 3x2 = 74 => x2 = 74/3 => x không thỏa mãn

c) \(\left(19x+2\cdot5^2\right):14=\left(13-8\right)^2-4^2\)

=> \(\left(19x+2\cdot25\right):14=5^2-4^2=9\)

=> \(\left(19x+50\right):14=9\)

=> \(19x+50=126\)

=> \(19x=76\)

=> x = 4

d) \(x:\frac{1}{2}+x:\frac{1}{4}+x:\frac{1}{8}+x:\frac{1}{16}+x:\frac{1}{32}=343\)

=> \(x\cdot2+x\cdot4+x\cdot8+x\cdot16+x\cdot32=343\)

=> \(x\left(2+4+8+16+32\right)=343\)

=> x . 62 = 343

=> x = 343/62

15 tháng 2 2022
7236 nhan 3 thì bang may
29 tháng 9 2017

\(\left(3x-2^4\right)\cdot7^3=2\cdot7^4\)

\(3x-2^4=7^4\cdot2:7^3=7\cdot2=14\)

\(3x-16=14\)

\(3x=14+16=30\)

\(x=\frac{30}{3}=10\)

vậy x=10

29 tháng 9 2017

a, -2 phần 3