CÁI / NÀY LÀ PHÂN SỐ À

=1.4/90+1.5/90+1.2/90+1.10/90

=4/90+5/90+2/90+10/90

=4+5+2+10/90

=21/90

=7/30

16,8 : 0,25 + 16,8 : 0,2 + 16,8 + 16,8 * 90

=16,8 * 4 + 16,8 * 5 + 16,8 + 16,8 *90

=16,8 *(4+5+1+90)

=16,8*100

=1680

Yo,sup. Kết quả ta có:

=16,8 x 4 + 16,8 x 5 + 16,8 x 1 +16,8 x 90

=16,8 x (4 + 5 + 1 + 90)

=16,8 x 100

=1680

a: =(41,5+15,5)x4=57x4=228

b: =13,6x8+34,4x8=50x8=400

c: =135 giây+135 giây+135 giây x8

=135x10=1350 giây

1

1/90:0.25+1/90:0.5+1/90:0.125-1/90:0.1

= 1/90 x 4 + 1/90 x 5 + 1/90 x 2 + 1/90 x 8 - 1/90 x 10

= 1/90 x ( 4+5+2+8-10)

= 1/90 x 9

= 1/10

k nha!Cảm ơn nhiều!

1)

a) \(x-158:6=40\)

\(\Rightarrow x-\frac{79}{3}=40\) \(\Rightarrow x=40+\frac{79}{3}=\frac{199}{3}\)

c) \(x+0,25=\frac{43}{4}-\frac{18}{5}\)

\(\Rightarrow x+\frac{1}{4}=\frac{143}{20}\)\(\Rightarrow x=\frac{143}{20}-\frac{1}{4}=\frac{69}{10}\)

b) \(x-1,75.4=2,5\)

\(\Rightarrow x-7=2,5\)\(\Rightarrow x=2,5+7=9,5\)

d) \(x.0,125=3,6+2,8\)

\(\Rightarrow x.0,125=6,4\) \(\Rightarrow x=6,4:0,125=51,2\)

2)

Ta có: S1 = 3 + 15 + 87 + x + 12

\(\Rightarrow S1=117+x\)

mà 117 chia hết cho 3 nên để S1 chia hết cho 3 thì x phải chia hết cho 3.

= 47/84

Dấu \(.\)là dấu nhân nhé

Ta có : 
\(B=\frac{1}{2}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}+\frac{1}{132}\)

\(\Rightarrow B=\frac{1}{2}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}+\frac{1}{11.12}\)

\(\Rightarrow B=\frac{1}{2}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{11}+\frac{1}{11}-\frac{1}{12}\)

\(\Rightarrow B=\frac{1}{2}+\frac{1}{7}-\frac{1}{12}\)

\(\Rightarrow B=\frac{42}{84}+\frac{12}{84}-\frac{7}{84}\)

\(\Rightarrow B=\frac{47}{84}\)

K mik nha