Tính:
4 - 1 = 4 - 2 = 3 + 1 = 1 + 2 =
3 - 1 = 3 - 2 = 4 - 3 = 3 - 1 =
2 - 1 = 4 - 3 = 4 - 1 = 3 - 2 =
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Lời giải chi tiết:
3 + 1 = 4 | 4 – 2 = 2 | 1 + 2 = 3 |
4 – 3 = 1 | 3 – 2 = 1 | 3 – 1 = 2 |
4 – 1 = 3 | 4 – 3 = 1 | 3 – 2 = 1 |
a)\(\dfrac{2}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}+\dfrac{1}{3}\right).\dfrac{4}{5}=1.\dfrac{4}{5}=\dfrac{4}{5}\)
b)\(\dfrac{2}{3}.\dfrac{4}{5}-\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}-\dfrac{1}{3}\right).\dfrac{4}{5}=\dfrac{1}{3}.\dfrac{4}{5}=\dfrac{4}{15}\)
a) \(\dfrac{2}{3}\times\dfrac{4}{5}+\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{4}{5}\times1=\dfrac{4}{5}\)
b) \(\dfrac{2}{3}\times\dfrac{4}{5}-\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}-\dfrac{1}{3}\right)=\dfrac{4}{5}\times\dfrac{1}{3}=\dfrac{4}{15}\)
c) \(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}+\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\times\left(\dfrac{1}{2}+\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{2}{3}=\dfrac{8}{9}\)
d) \(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}-\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{1}{3}=\dfrac{4}{9}\)
2 + 3 = 5 4 + 1 = 5 1 + 2 = 3 3 + 1 = 4 4 + 0 = 4
3 + 2 = 5 1 + 4 = 5 2 + 1 = 3 1 + 3 = 4 0 + 4 = 4
1 - 1/2 + 2 - 2/3 + 3 - 3/4 + 4 - 1/4 - 3 - 1/3 - 2 - 1/2 - 1
=(1-1)+(2-2)+(3-3)+\(\left(-\frac{1}{2}-\frac{1}{2}\right)+\left(-\frac{2}{3}-\frac{1}{3}\right)+\left(\frac{-3}{4}-\frac{1}{4}\right)\)+4
=0+(-3)+4
=1
Bài 1
a) 3 2/5 - 1/2
= 17/5 - 1/2
= 34/10 - 5/10
= 29/10
b) 4/5 + 1/5 × 3/4
= 4/5 + 3/20
= 16/20 + 3/20
= 19/20
c) 3 1/2 × 1 1/7
= 7/2 × 8/7
= 4
d) 4 1/6 : 2 1/3
= 25/6 : 7/3
= 25/14
Bài 2
a) 3 × 1/2 + 1/4 × 1/3
= 3/2 + 1/12
= 18/12 + 1/12
= 19/12
b) 1 4/5 - 2/3 : 2 1/3
= 9/5 - 2/3 : 7/3
= 9/5 - 2/7
= 63/35 - 10/35
= 53/35
Lời giải chi tiết:
5 – 1 = 4 | 4 – 1 = 3 | 3 – 1 = 2 | 2 + 3 = 5 |
5 – 2 = 3 | 4 – 2 = 2 | 3 – 2 = 1 | 3 + 2 = 5 |
5 – 3 = 2 | 4 – 3 = 1 | 2 – 1 = 1 | 5 – 2 = 3 |
5 – 4 = 1 | 5 – 3 = 2 |
5-1=4 4-1=3 3-1=2 2+3=5
5-2=3 4-2=2 3-2=1 3+2=5
5-3=2 4-3=1 2-1=1 5-2=3
5-4=1 5-3=2
\(S=\dfrac{1}{1x2}+\dfrac{1}{2x3}+\dfrac{1}{3x4}+\dfrac{1}{4x5}+...\dfrac{1}{nx\left(n+1\right)}\)
\(S=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...\dfrac{1}{n}-\dfrac{1}{n+1}\)
\(S=1-\dfrac{1}{n+1}=\dfrac{n}{n+1}\)
\(T=\dfrac{3}{1x2}+\dfrac{3}{2x3}+\dfrac{3}{3x4}+\dfrac{3}{4x5}+...\dfrac{3}{nx\left(n+1\right)}\)
\(T=3x\left[\dfrac{1}{1x2}+\dfrac{1}{2x3}+\dfrac{1}{3x4}+\dfrac{1}{4x5}+...\dfrac{1}{nx\left(n+1\right)}\right]\)
\(T=3x\left[1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...\dfrac{1}{n}-\dfrac{1}{n+1}\right]\)
\(T=3x\left(1-\dfrac{1}{n+1}\right)=\dfrac{3xn}{n+1}\)
Lời giải chi tiết:
0 + 1 = 1 | 0 + 2 = 2 | 0 + 3 = 3 | 0 + 4 = 4 |
1 + 1 = 2 | 1 + 2 = 3 | 1 + 3 = 4 | 1 + 4 = 5 |
2 + 1 = 3 | 2 + 2 = 4 | 2 + 3 = 5 | |
3 + 1 = 4 | 3 + 2 = 5 | ||
4 + 1 = 5 |
Thực hiện phép cộng trong phạm vi 5 rồi điền số còn thiếu vào chỗ trống.
0 + 1 = 1 0 + 2 = 2 0 + 3 = 3 0 + 4 = 4
1 + 1 = 2 1 + 2 = 3 1 + 3 = 4 1 + 4 = 5
2 + 1 = 3 2 + 2 = 4 2 + 3 = 5
3 + 1 = 4 3 + 2 = 5
4 + 1 = 5
0 + 1 = 1 0 + 2 = 2 0 + 3 = 3 0 + 4 = 4
1 + 1 = 2 1 + 2 = 3 1 + 3 = 4 1 + 4 = 5
2 + 1 = 3 2 + 2 = 4 2 + 3 = 5
3 + 1 = 4 3 + 2 = 5
4 + 1 = 5
Học tốt ~~
Thực hiện phép trừ rồi điền kết quả vào chỗ trống.
4 - 1 = 3 4 - 2 = 2 3 + 1 = 4 1 + 2 = 3
3 - 1 = 2 3 - 2 = 1 4 - 3 = 1 3 - 1 = 2
2 - 1 = 1 4 - 3 = 1 4 - 1 = 3 3 - 2 = 1
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