quy đồng ra nhé

( 7/6 + 5/16 + 3/16) x 1/5

= ( 7/6 + 1/2) x 1/5

= ( 7/6 + 3/6) x 1/5

= 10/6 x 1/5

= 5/3 x 1/5 

=1/3

8/5

686/65

5/7

can loi giai

a, \(\left(\frac{4}{9}.\frac{3}{7}\right).\frac{7}{4}=\frac{4}{9}\left(\frac{3}{7}.\frac{7}{4}\right)=\frac{4}{9}.\frac{3}{4}=\frac{3}{9}=\frac{1}{3}\)

b, \(\left(\frac{6}{5}.\frac{4}{5}\right).\frac{25}{16}=\frac{6}{5}\left(\frac{4}{5}.\frac{25}{16}\right)=\frac{6}{5}.\frac{5}{4}=\frac{6}{4}=\frac{3}{2}\)

c, \(\left(\frac{7}{8}.\frac{16}{9}\right).\frac{3}{14}=\frac{7}{8}\left(\frac{16}{9}.\frac{3}{14}\right)=\frac{7}{8}.\frac{8}{21}=\frac{7}{21}=\frac{1}{3}\)

a, $\left(\frac{4}{9}.\frac{3}{7}\right).\frac{7}{4}=\frac{4}{9}\left(\frac{3}{7}.\frac{7}{4}\right)=\frac{4}{9}.\frac{3}{4}=\frac{3}{9}=\frac{1}{3}$

b, $\left(\frac{6}{5}.\frac{4}{5}\right).\frac{25}{16}=\frac{6}{5}\left(\frac{4}{5}.\frac{25}{16}\right)=\frac{6}{5}.\frac{5}{4}=\frac{6}{4}=\frac{3}{2}$

c, $\left(\frac{7}{8}.\frac{16}{9}\right).\frac{3}{14}=\frac{7}{8}\left(\frac{16}{9}.\frac{3}{14}\right)=\frac{7}{8}.\frac{8}{21}=\frac{7}{21}=\frac{1}{3}$

( 4/9 x 3/7 ) x 7/4 = 4/9 x ( 3/7 x 7/4 ) =4/9 x 21/28 = 84/252

( 6/5 x 4/5 ) x 25/16 = ( 25/16 x 4/5 ) x 6/5 = 100/80 x 6/5 = 600/400

Ta có: \(\begin{array}{l}2{\rm{x}} + 5 = 16\\2{\rm{x}} = 16 - 5\\2{\rm{x}} = 11\\x = \frac{{11}}{2}\end{array}\)

Như vậy, bạn Vuông giải đúng, bạn Tròn giải sai

a) \(\dfrac{7}{9}\times\dfrac{13}{25}\times\dfrac{9}{7}=\left(\dfrac{7}{9}\times\dfrac{9}{7}\right)\times\dfrac{13}{25}=1\times\dfrac{13}{25}=\dfrac{13}{25}\)

b) \(\dfrac{5}{9}\times\dfrac{21}{25}+\dfrac{21}{25}\times\dfrac{4}{9}\)

\(=\dfrac{21}{25}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\)

\(=\dfrac{21}{25}\times1=\dfrac{21}{25}\)

c) \(\dfrac{19}{5}\times\dfrac{11}{16}-\dfrac{9}{5}\times\dfrac{11}{16}\)

\(=\dfrac{11}{16}\times\left(\dfrac{19}{5}-\dfrac{9}{5}\right)\)

\(=\dfrac{11}{16}\times2=\dfrac{22}{16}=\dfrac{11}{8}\)

=5/16x(18/35 - 2/7)

=5/16x 8/35

=1/14

Lời giải:

$\frac{18}{35}\times \frac{5}{16}-\frac{5}{16}\times \frac{2}{7}$

$=\frac{5}{16}\times (\frac{18}{35}-\frac{2}{7})$

$=\frac{5}{16}\times \frac{8}{35}=\frac{1}{14}$

Đề bài sai, pt này ko giải được

Đề đúng: \(\dfrac{4x^2+16}{x^2+6}=...\)

Mẫu số bên trái thừa mất số 1

X - 6/5 = 4

X = 4 + 6/5

X= 26/5

X x 4/5 = 23/20

X = 23/20 : 4/5

X = 23/16

5.x - 9 = 5 + 3.x

5x - 3x = 5 + 9

2x = 14

x = 14 : 2

x = 7

--------------------

(5x + 1)² = 36/49

5x + 1 = 6/7 hoặc 5x + 1 = -6/7

*) 5x + 1 = 6/7

5x = 6/7 - 1

5x = -1/7

x = -1/7 : 5

x = -1/35

*) 5x + 1 = -6/7

5x = -6/7 - 1

5x = -13/7

x = -13/7 : 5

x = -13/35

Vậy x = -13/35; x = -1/35

--------------------

2ˣ⁻¹ = 16

2ˣ⁻¹ = 2⁴

x - 1 = 4

x = 4 + 1

x = 5