B1

a) 17 b) 6 c) 112 d)9687

B2

100-x=33

x=100-33

x= 67

Ko bít

22222222222222222

60000 – 20000 – 10000 = 40000 – 10000 = 30000

60000 – (20000 + 10000) = 60000 – 30000 = 30000

60000 – 20000 – 10000 = 40000 – 10000 = 30000

60000 – (20000 + 10000) = 60000 – 30000 = 30000

Có (2 x 7 )x2+(5x2)

=14x2+10

=28+10

=38

Gấp đôi ==> x2

Thêm ==> +(biểu thức)

Ta có phép tính:

2x7x2+5x2

=2x14+5x2

=2x(14+5)

=2x19

=38

\(a,2\times3=6\)

\(6\times2=12\)

\(10\times2=20\)

\(1\times2=2\)

\(b,5\times7=35\)

\(9\times5=45\)

\(5\times8=40\)

\(1\times5=5\)

a) 30000 + (20000 + 40000) = 90000

    30000 + 20000 + 40000 = 90000

    60000 - (30000 + 20000) = 10000

    60000 - 30000 - 20000 = 10000

b) 40000 x 2 : 4 = 20000

    36000 : 6 x 3 = 18000

    20000 x 4 : 8 = 10000

    60000 : 3 x 2 = 18000

C1: \(\left(\frac{3}{5}+\frac{4}{9}\right)\cdot\frac{3}{8}=\frac{47}{45}\cdot\frac{3}{8}=\frac{141}{360}=\frac{47}{120}\)

C2: \(\left(\frac{3}{5}+\frac{4}{9}\right)\cdot\frac{3}{8}=\frac{3}{5}\cdot\frac{3}{8}+\frac{4}{9}\cdot\frac{3}{8}=\frac{9}{40}+\frac{12}{72}=\frac{47}{120}\)

C1: ( \(\frac{3}{5}+\frac{4}{9}\) ) * \(\frac{3}{8}\) 

= \(\frac{47}{45}\) * \(\frac{3}{8}\) = \(\frac{47}{120}\) 

C2: Đề

= 3/5 * 3/8 + 4/9 * 3/8

= 9/40 + 1/6

= 47/120