321475 + 423507 x 2

= 321475 + 847014 = 1168489

=1168489 nhé

609 x 9 - 4845

= 5481 - 4845 = 636

a) 3 x 1/5 + 2/5 = 3/5 + 2/5 = 1

b) 3 : 1/5 - 2/5 = 15 - 2/5 = 73/5

bài 2 :
a) X x 1/2 = 1 - 1/5

    X x 1/2 = 4/5 

           X   = 4/5 : 1/2

           X   = 8/5 

vậy x =...

b) x : 1/3 = 1 + 1/5

    x : 1/3 = 6/5

          x   = 6/5 x 1/3

          x   = 2/5

vậy x =...

843275 - 123568 x 5

= 843275 - 617840 = 225435

a,`9/5+2/5xx4/6=9/5+4/15=27/15+4/15=31/15`

b,`3/8xx2-6/7xx1/3=3/4-2/7=21/18-8/28=13/28`

a) 9/5+ 4/15

= 27/15+4/15

= 31/15

b) 3/4- 2/7

= 13/28

1306 x 8 + 24573

= 10448 + 24573 = 35021

66 589                      

\(\dfrac{3}{7}\times\dfrac{7}{9}\times\dfrac{1}{2}\)

\(=\dfrac{3\times7\times1}{7\times9\times2}\)

\(=\dfrac{21}{126}\)

\(=\dfrac{1}{6}\)

\(\dfrac{5}{8}\times4\times\dfrac{1}{2}\\ =\dfrac{5}{8}\times\dfrac{4}{1}\times\dfrac{1}{2}\\ =\dfrac{5\times4\times1}{8\times1\times2}\\ =\dfrac{20}{16}\\ =\dfrac{5}{4}\)

\(4\times\dfrac{1}{24}\times3\\ =\dfrac{4}{1}\times\dfrac{1}{24}\times\dfrac{3}{1}\\ =\dfrac{4\times1\times3}{1\times24\times1}\\ =\dfrac{12}{24}\\ =\dfrac{1}{2}\)

a: \(-2x\left(3x+4\right)+\left(2x+5\right)\left(9-7x\right)\)

\(=-6x^2-8x+18x-14x^2+45-35x\)

\(=-20x^2-25x+45\)

b: \(\left(x-5\right)^2-\left(4-x\right)\left(4+x\right)\)

\(=x^2-10x+25-\left(16-x^2\right)\)

\(=x^2-10x+25-16+x^2=2x^2-10x+9\)

c: \(\left(4x^2-12x+8\right):\left(x-2\right)\)

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

\(=\frac{4\left(x-2\right)\left(x-1\right)}{x-2}=4\left(x-1\right)=4x-4\)