công thúc nè
tính số số hạng : (số cuối -số đầu) / khoảng cách +1
tính tổng :(số cuối + số đầu)* số số hạng / 2
cho mình hỏi chút lopw 4 đã hc có nì rồi ah

a) 1 + 5 + 9 + 13 + ... + 393 + 397

= (1 + 397) x (\(\frac{397-1}{4}\) + 1) : 2

= 398 x \(\frac{397-1+4}{4}\) : 2

= (398 : 2) x \(\frac{397+3}{4}\)

= 199 x \(\frac{200}{4}\)

= 199 x 50 = 9950

a) 2024 . 33 + 2024 + 4048 . 33

= 2024 . 33 + 2024 . 1 + 2024 . 2 . 33

= 2024 . ( 33 + 1 + 66 )

= 2024 . 100

= 202400

2024×33+2024+4048×33=

\(\left(\right. 2024 + 4048 \left.\right) \times 33 + 2024\)

\(2024 + 4048 = 6072\)

\(6072 \times 33 = 200376\)

\(2024\): \(200376 + 2024 = 202400\)

b)
\(8 \times \frac{1}{6} + 8 \times \frac{2}{6} + 8 \times \frac{3}{6}\)
\(\frac{1}{6} + \frac{2}{6} + \frac{3}{6} = \frac{6}{6} = 1\)

\(8 \times 1 = 8\)

a)=82,5

b=3/8

4/5 : 2/9 x 2/9 : 4/5
= 4/5 x 9/2 x 2/9 x 5/4
= ( 4/5 x 5/4 ) x ( 9/2 x 2/9 )
= 1x1
= 1

\(\frac{4}{5}:\frac{2}{9}\times\frac{2}{9}:\frac{4}{5}\)

\(=\frac{4}{5}\times\frac{9}{2}\times\frac{2}{9}\times\frac{5}{4}\)

\(=\left(\frac{4}{5}\times\frac{5}{4}\right)\times\left(\frac{2}{9}\times\frac{9}{2}\right)\)

\(=1\times1\)

\(=1\)

a \(\frac{7}{6}\)

b \(\frac{5}{3}\)

\(a,\frac{2}{5}+\frac{1}{6}+\frac{3}{5}\)

\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{1}{6}\)

\(=1+\frac{1}{6}\)

\(=\frac{7}{6}\)

Hok tốt!~

24×4/6×3/4

24×1/2

12/1

24 x \(\frac{4}{6}\)x \(\frac{3}{4}\) =  \(\frac{24}{1}\) x \(\frac{4}{6}\) x \(\frac{3}{4}\)

                              = \(\frac{24x4x3}{1x6x4}\)

                              = \(\frac{6x4x4x3}{1x6x4}\)

                              =  3

\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)

\(=1:\frac{5}{6}\)

\(=1\times\frac{6}{5}\)

\(=\frac{6}{5}\)

\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)

\(=1:\frac{5}{6}\)

\(=1\times\frac{6}{5}\)

\(=\frac{6}{5}\)

Trả lời :

25 x 8 x 50 x 125 x 4 x 2

= ( 25 x 4 ) x ( 8 x 125 ) x ( 50 x 2 )

= 100 x 1000 x 100

= 100 000 000

~HT~

#sad

team lop 1,2,3

team lop4,5,6

team lop 7,8,9

team lop 10,11,12

team truong thanh

team thanh GV 😘😘😘💕

a)\(y=\frac{12x30}{15x36}\)=\(\frac{12x15x2}{15x12x3}\)=\(\frac{2}{3}\)

  b) \(\frac{21x12}{54x42}\)=\(\frac{21x6x2}{6x9x21x2}\)=\(\frac{1}{9}\)

a) \(\frac{12x30}{15x36}=\frac{4x3x3x10}{5x3x3x12}=\frac{4x10}{5x12}=\frac{2x2x5x2}{5x2x6}=\frac{4}{6}=\frac{2}{3}\)

b) \(\frac{21x12}{54x42}=\frac{3x7x3x4}{18x3x7x6}=\frac{3x4}{18x6}=\frac{3x4}{3x6x6}=\frac{4}{24}=\frac{1}{6}\)