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a)1/2x3/4+1/2x1/4
=1/2x(3/4+1/4)
=1/2x1
=1/2
b)3/5x1/8+3/5x23/8
=3/5x(1/8+23/8)
=3/5x3
=9/5
HT NHKK
a) 1/2 x 3/4 + 1/2 x 1/4 = 3/8 + 1/8 = 4/8
b) 3/5 x 1/8 + 3/5 x 23/8 = 3/40 + 69/40 = 72/40 = 9/5
Bài 1: Tính giá trị các biểu thức sau:
14 x 3 + 23 x 4
23 x 5 – 96 : 4
16 x 3 + 55 : 5
968 : 8 – 13 x 7
69 : 3 + 21 x 4
36 x 3 – 29 x 2
72 : ( 107 – 99)
5 x (145 – 123)
đề lại bị lỗi
Bài 1: Tính giá trị các biểu thức sau:
14 x 3 + 23 x 4 23 x 5 – 96 : 4 16 x 3 + 55 : 5 968 : 8 – 13 x 769 : 3 + 21 x 4 36 x 3 – 29 x 2 72 : ( 107 – 99) 5 x (145 – 123)
=> Thiếu phép tính
a)\(\frac{2}{3}:\frac{4}{9}+\frac{1}{3}:\frac{4}{9}\)
=\(\frac{4}{9}:\left(\frac{2}{3}+\frac{1}{3}\right)\)
=\(\frac{4}{9}:1=\frac{4}{9}\)
b
Tính nhanh mỗi biểu thức sau:
a, 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20
= (0 + 20) + (1 + 19) + (2 + 18) + (3 + 17) + (4 + 16) + (5 + 15) + (6 + 14) + (7 + 13) + (8 + 12) + (9 + 11) + 10
= 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 10
= 20 x 10 + 10
= 200 + 10
= 210
b, 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x (4 x 9 - 36)
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x (36 - 36)
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 0
= A x 0
= 0
c, (81 - 7 x 9 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= (81 - 63 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= (18 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= 0 :(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= 0 : A
= 0
d, (6 x 5 + 7 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (30 + 7 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (37 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= 0 x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= 0 x A
= 0
e, (11 x 9 - 100 + 1) : (1 x 2 x 3 x 4 x ... x 10)
= (99 - 100 + 1) : (1 x 2 x 3 x 4 x ... x 10)
= (99 + 1 - 100) : (1 x 2 x 3 x 4 x ... x 10)
= (100 - 100) : (1 x 2 x 3 x 4 x ... x 10)
= 0 : (1 x 2 x 3 x 4 x ... x 10)
= 0 : A
= 0
g, (m : 1 - m x 1) : (m x 2008 + m x 2008)
= (m - m) : (m x 2008 + m x 2008)
= 0 : (m x 2008 + m x 2008)
= 0 : A
= 0
h, (2 + 4 + 6 + 8 + m x n) x (324 x 3 - 972)
= (2 + 4 + 6 + 8 + m x n) x (972 - 972)
= (2 + 4 + 6 + 8 + m x n) x 0
= A x 0
= 0
l, (1 + 2 + 3 + ... + 99) x (13 x 15 - 12 x 15 - 15)
= (1 + 2 + 3 + ... + 99) x (15 x (13 - 12 - 1))
= (1 + 2 + 3 + ... + 99) x (15 x 0)
= (1 + 2 + 3 + ... + 99) x 0
= A x 0
= 0
i, (0 x 1 x 2 x...x 99 x 100) : (2 + 4 + 6 +...+ 98)
= 0 x : (2 + 4 + 6 +...+ 98)
= 0 x A
= 0
k, (0 + 1 + 2 +...+ 97 + 99) x (45 x 3 - 45 x 2 - 45)
= (0 + 1 + 2 +...+ 97 + 99) x (45 x (3 - 2 - 4))
= (0 + 1 + 2 +...+ 97 + 99) x (45 x 0)
= (0 + 1 + 2 +...+ 97 + 99) x 0
= A x 0
= 0
a, = 4/7 * { 2/3 +1/3 }
=4/7 * 3 /3 =4/7 * 1 = 4/7
b, =5/8 * 21/21 = 5/8 * 1= 5/8
c, { 4/5 + 2 } * 5/4 tức là 4/5 * 5/4 + 2 * 5/4
= 20/20 +5/2 = 2/2 + 5/2 = 7/2
tk cho mình nha
7/15+4/5= 7/15+12/15= 19/15
2/3-3/8= 16/24-9/24= 7/24
\(\frac{4}{5}\times\frac{5}{8}=\frac{4\times5}{5\times8}=\frac{20}{40}\)\(=\frac{1}{2}\)
1/2:2/5=5/4
\(\frac{7}{15}+\frac{4}{5}=\frac{7}{15}+\frac{12}{15}=\frac{19}{15}\)
\(\frac{2}{3}-\frac{3}{8}=\frac{16}{24}-\frac{9}{24}=\frac{7}{24}\)
\(\frac{4}{5}\times\frac{5}{8}=\frac{4}{8}=\frac{1}{2}\)
\(\frac{1}{2}\div\frac{2}{5}=\frac{1}{2}\times\frac{5}{2}=\frac{5}{4}\)
a)2/3*4/7+1/3*4/7=(2/3+1/3)*4/7=1*4/7=4/7
b)5/8*3/7*7/3=5/8*1=5/8
c)(4/5+2)*5/4=4/5*5/4+2=1+2=3
a)1/2x3/4+1/2x1/4
=1/2x(1/4+3/4)
=1/2x1
=1/2
b)3/5x1/8+3/5x23/8
=3/5x(1/8+23/8)
=3/5x2
=9/5
HT
a/= \(\frac{1}{2}\)
b/\(\frac{9}{5}\)
Hok tốt!