Lời giải:

b.

$\frac{2x}{3}=8$

$\Leftrightarrow 2x=3.8=24$

$\Leftrightarrow x=24:2=12$
d.

$\frac{6}{5}x=-9$

$\Leftrightarrow x=-9: \frac{6}{5}=\frac{-15}{2}$

f.

$\frac{2-3x}{4}=\frac{4x-5}{5}$

$\Leftrightarrow 5(2-3x)=4(4x-5)$

$\Leftrightarrow 10-15x=16x-20$

$\Leftrightarrow 30=31x$

$\Leftrightarrow x=\frac{30}{31}$

h.

$\frac{10-3x}{2}=\frac{6x+1}{3}$

$\Leftrightarrow 3(10-3x)=2(6x+1)$

$\Leftrightarrow 30-9x=12x+2$

$\Leftrightarrow 28=21x$

$\Leftrightarrow x=\frac{28}{21}=\frac{4}{3}$

1: Ta có: \(20-2\left(x+4\right)=4\)

\(\Leftrightarrow2\left(x+4\right)=16\)

\(\Leftrightarrow x+4=8\)

hay x=4

5: Ta có: \(\left(x+1\right)^3=27\)

\(\Leftrightarrow x+1=3\)

hay x=2

c ( 3x² -6 ) - 43 = 5³

( 3x² -6 ) - 43 = 125

3x² -6=125+43

3x² -6=168

3x²=168+6

3x²=174

x²=174:3

x²=58(đề sai)

d) 3x + 2x ( 2³ . 5 - 3² . 4 ) + 5² = 4⁴

3x + 2x ( 8 . 5 - 9 . 4 ) + 25 = 256

3x + 2x.4 + 25 = 256

3x + 2x.4=256-25

3x + 2x.4=231

(3+2).x.4=231

5x.4=231

5x=231:4

5x=57,75

x=57,75:5

x=11,55

e) 720 : [ 41 - ( 2x - 5 ) ] = 2³ . 5

720 : [ 41 - ( 2x - 5 ) ] =40

41 - ( 2x - 5 )=720:40

41 - ( 2x - 5 )=18

 2x - 5=41-18

 2x - 5=23

2x=23+5

2x=28

x=28:2

x=14

thu gọn 7^3*7^5

Oh no nhiều kí tự đặc biệt quá

dễ quá mình ko làm  đc 

\(\dfrac{5}{x}+1+\dfrac{4}{x}+1=\dfrac{3}{-13}\\ \Rightarrow\dfrac{9}{x}+2=-\dfrac{3}{13}\\ \Rightarrow\dfrac{9}{x}=-\dfrac{59}{13}\\ \Rightarrow x=-\dfrac{207}{59}\)

a. \(\dfrac{5}{x+1}+\dfrac{4}{x+1}=\dfrac{-3}{13}\)

ĐKXĐ: x ≠ -1

⇔ \(\dfrac{65}{13\left(x+1\right)}+\dfrac{52}{13\left(x+1\right)}=\dfrac{-3\left(x+1\right)}{13\left(x+1\right)}\)

⇔ 65 + 52 = -3(x + 1)

⇔ 117 = -3x - 3

⇔ 117 + 3 = -3x

⇔ 120 = -3x 

⇔ x = \(\dfrac{120}{-3}=-40\) (TM)

b. -x + 2 + 2x + 3 + x + \(\dfrac{1}{4}\) + 2x + \(\dfrac{1}{6}\) = \(\dfrac{8}{3}\)

⇔ -x + 2x + x + 2x = \(\dfrac{8}{3}-\dfrac{1}{6}-\dfrac{1}{4}-3-2\)

⇔ 4x = -2,75

⇔ x = \(\dfrac{-2,75}{4}=\dfrac{-11}{16}\)

c. \(\dfrac{3}{2x+1}+\dfrac{10}{4x+2}-\dfrac{6}{6x+2}\) = \(\dfrac{12}{26}\)

⇔  \(\dfrac{3}{2x+1}+\dfrac{10}{2\left(2x+1\right)}-\dfrac{6}{2\left(3x+1\right)}=\dfrac{12}{26}\)

⇔ \(\dfrac{312\left(3x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\) + \(\dfrac{520\left(3x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\) - \(\dfrac{312\left(2x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\)

= \(\dfrac{48\left(2x+1\right)\left(3x+1\right)}{104\left(2x+1\right)\left(3x+1\right)}\)

⇔ 312(3x +1) + 520(3x + 1) - 312(2x + 1) = 48(2x + 1)(3x + 1)

⇔ 936x + 312 + 1560x + 520 - 624x - 312 = (96x + 48)(3x + 1)

⇔ 936x + 312 + 1560x + 520 - 624x - 312 = 288x² + 96x + 144x + 48

⇔ 936x + 1560x - 624x - 96x - 144x - 288x² = 48 - 312 - 520 + 312

⇔ 1632x - 288x² = -472

⇔ -288x² + 1632x + 472 = 0 (Tự giải tiếp, dùng phương pháp tách hạng tử)

⇔ x = 5,942459684 \(\approx\) 6

c: Ta có: \(\dfrac{3}{2x+1}+\dfrac{10}{4x+2}-\dfrac{6}{6x+3}=\dfrac{12}{26}\)

\(\Leftrightarrow\dfrac{3}{2x+1}+\dfrac{5}{2x+1}-\dfrac{2}{2x+1}=\dfrac{6}{13}\)

\(\Leftrightarrow2x+1=13\)

hay x=6

a)x^m+4+x^m+3-x-1

=(x^m+4-x)+(x^m+3-1)

=x(x^m+3-1)+(x^m+3-1)

=(x+1)(x^m+3-1)

Với x=-2 ta có:... bn tự thay

b)x⁶-x⁴+2x³+2x²=x⁶-2x⁵+2x⁴+2x⁵-4x⁴+4x³+x⁴-2x³+2x²

=x⁴(x²-2x+2)+2x³(x²-2x+2)+x²(x²-2x+2)

=(x⁴+2x³+x²)(x²-2x+2)

=[x²(x²+2x+1)](x²-2x+2)

=x²(x+1)²(x²-2x+2)

Với x=-2 bn tự thay nhé h mk bận

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