5.8*3*3=52,2

ban oi hinh nhu ban lam sai roi

a) 4,25 kg x 3 = 12.75 kg.
b) 5,8 cm² x 3 + 5,8 cm² x 2 = 5,8 cm2 x 5 = 29 cm² 
c) 3,6 ha x 1 + 3,6 ha x 9 = 3,6 ha x 10 = 36 ha.
 

a)4.25kg*3=12.75kg

b)5.8m2+5.8m2*3+5.8m2=29m2

c)3.6ha+3.6ha*9=116.64ha

= 5,8m²(1 + 3 + 1)

= 5,8m²x5

= 29m²

= 5.8m2 x 1 + 5.8cm2 x3 + 5.8cm2 x 1

= 5.8cm2 x ( 1+ 3+ 1)

=5.8cm2 x 5

=29 cm2

Đề hình như bị sai ban ơi sửa lại

\(A=\dfrac{3}{2.5}+\dfrac{3}{5.8}+\dfrac{3}{8.11}+...+\dfrac{3}{92.95}\)

\(A=3\left(\dfrac{1}{2.5}+\dfrac{1}{5.8}+\dfrac{1}{8.11}+...+\dfrac{1}{92.95}\right)\)

\(A=3.\dfrac{1}{3}\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{92}-\dfrac{1}{95}\right)\)

\(A=\dfrac{1}{2}-\dfrac{1}{95}\)

\(A=\dfrac{93}{190}\)

\(B=\dfrac{2}{2.5}+\dfrac{2}{5.8}+\dfrac{2}{8.11}+...+\dfrac{2}{92.95}\)

\(3B=2\left(\dfrac{1}{2.5}+\dfrac{1}{5.8}+\dfrac{1}{8.11}+...+\dfrac{1}{92.95}\right)\)

\(3B=2.\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{92}-\dfrac{1}{95}\right)\)

\(3B=2\left(\dfrac{1}{2}-\dfrac{1}{95}\right)\)

\(3B=2.\dfrac{93}{190}\)

\(3B=\dfrac{93}{95}\)

\(\Rightarrow B=\dfrac{31}{95}\)

=5,8(1+3+5+1)=58

=5.8 x (3+5)
=5.8 x 8
=29

=1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14

=1/2-1/14

=7/14-1/14=6/14=3/7