\(\dfrac{13}{50}+9\%+\dfrac{41}{100}+0,24\)

\(=0,26+0,09+0,41+0,24\)

\(=\left(0,26+0,24\right)+\left(0,09+0,41\right)\)

\(=0,5+0,5\)

\(=1\)

26%+9%+41%+24%=100%

1

= 1

13/50=0,26

9%=0,09

41/100=0,41

=>0,26+0,09+0,41+0,26=1

\(\dfrac{13}{50}+9\%+\dfrac{41}{100}+0,24\)

\(=\dfrac{13}{50}+\dfrac{9}{100}+\dfrac{41}{100}+\dfrac{6}{25}\)

\(=\dfrac{13}{50}+\dfrac{9}{100}+\dfrac{41}{100}+\dfrac{12}{50}\)

\(=\left(\dfrac{13}{50}+\dfrac{12}{50}\right)+\left(\dfrac{9}{100}+\dfrac{41}{100}\right)\)

\(=\dfrac{25}{50}+\dfrac{50}{100}\)

\(=\dfrac{25}{50}+\dfrac{25}{50}\)

\(=\dfrac{50}{50}=1\)

\(\dfrac{13}{50}+9\%+\dfrac{41}{100}+0,24\)

\(=\dfrac{26}{100}+\dfrac{9}{100}+\dfrac{41}{100}+\dfrac{24}{100}\)

\(=\left(\dfrac{26}{100}+\dfrac{24}{100}\right)+\left(\dfrac{9}{100}+\dfrac{41}{100}\right)\)

\(=\dfrac{50}{100}+\dfrac{50}{100}=\dfrac{1}{2}+\dfrac{1}{2}=\dfrac{2}{2}=1\)

Bài 3

a,26/100+0,009+41/100+0,24

0,26+0,09+0,41+0,24

(0,26+0,24)+(0,09+0,41)

0,5+0,5

=1

b,9+1/4+6+2/7+7+3/5+8+2/3+2/5+1/3+5/7+3/4

(9+6+7+8)+(2/7+5/7)+(1/4+3/4)+(3/5+2/5)+(2/3+1/3)

30+1+1+1+1

=34

Bài 4,5 khó quá mik ko bít lamf^^))

Bài 5: vì \(\dfrac{3}{11}\) = \(\dfrac{3\times5}{11\times5}\) = \(\dfrac{15}{55}\)

Vậy Khi giữ nguyên tử số thì số cần thêm vào mẫu số là: 

              55 - 39 = 16

Đáp số: 16 

Bài 4: a, \(\dfrac{2008}{2009}\) < 1; \(\dfrac{10}{9}\) > 1

           \(\dfrac{2008}{2009}\) < \(\dfrac{10}{9}\)

         b, \(\dfrac{1}{a+1}\) và \(\dfrac{1}{a-1}\)

Ta có: a + 1 > a - 1 ⇒ \(\dfrac{1}{a+1}\) < \(\dfrac{1}{a-1}\)

15 - 3/7 rồi bạn tự tính nha

\(15-\dfrac{x}{2}=\dfrac{3}{7}\)

\(\dfrac{x}{2}=15-\dfrac{3}{7}=\dfrac{15\cdot7-3}{7}=\dfrac{102}{7}\)

\(x=\dfrac{102}{7}\cdot2=\dfrac{204}{7}\)

\(15-\dfrac{x}{2}=\dfrac{3}{7}\)

\(\dfrac{x}{2}=15-\dfrac{3}{7}\)

\(\dfrac{x}{2}=\dfrac{102}{7}\)

\(x\times7=102\times2\)

\(x\times7=204\)

\(x=204\div7\)

\(x=\dfrac{204}{7}\)

\(\dfrac{19\times2\times5}{19\times3\times5}=\dfrac{2}{3}\)

đúng òi

Áp dụng tính chất dãy tỉ số bằng nhau:\(\dfrac{\left(5z-3y\right)+\left(3x-2z\right)+\left(2y-5x\right)}{2+5+3}\)

=\(\dfrac{\left(3x-5x\right)+\left(-3y+2y\right)+\left(5z-2z\right)}{2+5+3}\)

=\(\dfrac{-2x-y+3z}{2+5+3}\)(???!!!!)

=\(\dfrac{-2x}{2}=\dfrac{-y}{5}=\dfrac{3z}{3}\)

=\(\dfrac{2}{-2x}=\dfrac{5}{-y}=\dfrac{3}{3z}\)

tớ xin chịu trận vì ko chứng minh được :(((

nó lại ra như thế này

125/90=25/18

84/91=12/13

75/45=25/15=5/3

125/90=25/18

84/91=12/13

75/45=25/15=5/3

6/7=18/21=54/63=104/126

125/90 = 25/18 

84/91 = 12/13

75/45 = 25/15 = 5/3

6/7 = 18/21 = 54/63 = 108/126

A = \(\dfrac{13}{50}\) + 9% + 41/100 + 0,24

A = 0,26 + 0,09 + 0,41 + 0,24

A = (0,26 + 0,24) + ( 0,09 + 0,41)

A = 0,5 + 0,5

A = 1

em cảm ơn cô