tính hợp lý 1 + 1/2(1+2) +1/3(1+2+3)+1/4(1+2+3+4)+...+1/16(1+2+3+4+...+16)
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1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/16(1+2+3+4+...+16) tính hợp lý
Bài 1: tínha. 1/3-(-1và2/5)+(-3và1/4) b.5/4-(-3và1/2)-7/10c.3/2-[(-4/7)-(1/2+5/8)]Bài 2: thực hiện phép tính bằng cách hợp lý a. A(1/2-7/13-1/3)+(-6/13+1/2+1và1/3)b.B0,75+2/5+(1/9-1và1/2+5/4)c.(-5/9).3/11+(-13/18).3/11d.(-2/3).3/11+(-16/9).3/11e.(-1/4).(-2/13)-7/24.(-2/13)f.(-1/27).3/7+(5/9).(-3/7)g.(-1/5+3/7):2/11+(-4/5+4/7):2/11bài 3: thực hiện phép tính a.0,3-4/9:4/3.6/5+1b.1+2:(2/3-1/6).(-2,25)c.[(1/4-0,5).2+8/3]:2d.[(3/8-5/12).6+1/3].4e.(4/5-1):3/5-2/3.0,5f.0,8:{0,2-7.[1/6+(5/21-5/14)]}Bài...
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Bài 1: tính
a. 1/3-(-1và2/5)+(-3và1/4)
b.5/4-(-3và1/2)-7/10
c.3/2-[(-4/7)-(1/2+5/8)]
Bài 2: thực hiện phép tính bằng cách hợp lý
a. A=(1/2-7/13-1/3)+(-6/13+1/2+1và1/3)
b.B=0,75+2/5+(1/9-1và1/2+5/4)
c.(-5/9).3/11+(-13/18).3/11
d.(-2/3).3/11+(-16/9).3/11
e.(-1/4).(-2/13)-7/24.(-2/13)
f.(-1/27).3/7+(5/9).(-3/7)
g.(-1/5+3/7):2/11+(-4/5+4/7):2/11
bài 3: thực hiện phép tính
a.0,3-4/9:4/3.6/5+1
b.1+2:(2/3-1/6).(-2,25)
c.[(1/4-0,5).2+8/3]:2
d.[(3/8-5/12).6+1/3].4
e.(4/5-1):3/5-2/3.0,5
f.0,8:{0,2-7.[1/6+(5/21-5/14)]}
Bài 4: tính theo cách hợp lý
a.4/15-(2,9-11/15)
b.(-36,75)+(37/10-63,25)-(-6,3)
c. 6,5+(-10/17)-(-7/2)-7/17
d.(-39,1).13/25-60,9.13/25
e. -5/12-3,7-7/12-6,3
f.2,8.-6/13-7,2-2,8.7/13
4:
a: =4/15-2,9+11/15=1-2,9=-1,9
b: \(=-36,75+3,7-63,25+6,3=10-100=-90\)
c: \(=6,5+3,5-\dfrac{10}{17}-\dfrac{7}{17}=10-1=9\)
d: \(=\dfrac{13}{25}\left(-39,1-60,9\right)=\dfrac{13}{25}\left(-100\right)=-52\)
e: =-5/12-7/12-3,7-6,3=-1-10=-11
f: =2,8(-6/13-7/13)-7,2=-2,8-7,2=-10
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Bài 2: thực hiện phép tính bằng cách hợp lý a. A(1/2-7/13-1/3)+(-6/13+1/2+1và1/3)b.B0,75+2/5+(1/9-1và1/2+5/4)c.(-5/9).3/11+(-13/18).3/11d.(-2/3).3/11+(-16/9).3/11e.(-1/4).(-2/13)-7/24.(-2/13)f.(-1/27).3/7+(5/9).(-3/7)g.(-1/5+3/7):2/11+(-4/5+4/7):2/11
Đọc tiếp
Bài 2: thực hiện phép tính bằng cách hợp lý
a. A=(1/2-7/13-1/3)+(-6/13+1/2+1và1/3)
b.B=0,75+2/5+(1/9-1và1/2+5/4)
c.(-5/9).3/11+(-13/18).3/11
d.(-2/3).3/11+(-16/9).3/11
e.(-1/4).(-2/13)-7/24.(-2/13)
f.(-1/27).3/7+(5/9).(-3/7)
g.(-1/5+3/7):2/11+(-4/5+4/7):2/11
`@` `\text {Ans}`
`\downarrow`
`a.`
`A=(1/2-7/13-1/3)+(-6/13+1/2+1 1/3)`
`= 1/2 - 7/13 - 1/3 - 6/13 + 1/2 + 1 1/3`
`= (1/2 + 1/2) + (-7/13 - 6/13) + (-1/3 + 1 1/3) `
`= 1 - 1 + 1`
`= 1`
`b.`
`B=0,75+2/5+(1/9-1 1/2+5/4)`
`= 3/4 + 2/5 + 1/9 - 3/2 + 5/4`
`= (3/4+5/4)+ 1/9 + 2/5 - 3/2`
`= 2 + 1/9 - 11/10`
`= 19/9 - 11/10`
`= 91/90`
`c.`
`(-5/9).3/11+(-13/18).3/11`
`= 3/11*[(-5/9) + (-13/18)]`
`= 3/11*(-23/18)`
`= -23/66`
`d.`
`(-2/3).3/11+(-16/9).3/11`
`= 3/11* [(-2/3) + (-16/9)]`
`= 3/11*(-22/9)`
`= -2/3`
`e.`
`(-1/4).(-2/13)-7/24.(-2/13)`
`= (-2/13)*(-1/4-7/24)`
`= (-2/13)*(-13/24)`
`= 1/12`
`f.`
`(-1/27).3/7+(5/9).(-3/7)`
`= 3/7*(-1/27 - 5/9)`
`= 3/7*(-16/27)`
`= -16/63`
`g.`
`(-1/5+3/7):2/11+(-4/5+4/7):2/11`
`=[(-1/5+3/7)+(-4/5+4/7)] \div 2/11`
`= (-1/5+3/7 - 4/5 + 4/7) \div 2/11`
`= [(-1/5-4/5)+(3/7+4/7)] \div 2/11`
`= (-1+1) \div 2/11`
`= 0 \div 2/11 = 0`
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Bài 1: Tính hợp lý. (nếu có thể)A 1/10+1/40+1/88+1/154+1/238+1/340B2 +1/547 . 3/211 - 546/547 - 4/547.211D 1/3+1/6+1/12+1/24+1/48E 1/2 - 1/4 + 1/8 - 1/16 +...+ 1/2048F 0,5 - 1/3 - 0,4 -5/7 - 1/6 + 4/35 - 1/41
Đọc tiếp
Bài 1: Tính hợp lý. (nếu có thể)
A= 1/10+1/40+1/88+1/154+1/238+1/340
B=2 +1/547 . 3/211 - 546/547 - 4/547.211
D= 1/3+1/6+1/12+1/24+1/48
E= 1/2 - 1/4 + 1/8 - 1/16 +...+ 1/2048
F= 0,5 - 1/3 - 0,4 -5/7 - 1/6 + 4/35 - 1/41
Giải:
A=1/10+1/40+1/88+1/154+1/238+1/340
A=1/2.5+1/5.8+1/8.11+1/11.14+1/14.17+1/17.20
A=1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20
A=1/2-1/20
A=9/20
D=1/3+1/6+1/12+1/24+1/48
D=1/3+1/2.3+1/3.4+1/4.6+1/6.8
D=1/3+1/2-1/3+1/3-1/4+1/2.(2/4.6+2/6.8)
D=1/3+1/2-1/4+1/2.(1/4-1/6+1/6-1/8)
D=1/3+1/4+1/2.(1/4-1/8)
D=1/3+1/4+1/2.1/8
D=1/3+1/4+1/16
D=31/48
F=0,5-1/3-0,4-4/7-1/6+4/35-1/41
F=1/2-1/3-2/5-4/7-1/6+4/35-1/41
F=1/6-(-6/35)-1/6+4/35-1/41
F=(1/6-1/6)+(6/35+4/35)-1/41
F=0+2/7-1/41
F=2/7+1/41
F=75/287
Chúc bạn học tốt!
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Tính nhanh
A= 1+ 1/2 (1+2) +1/3 (1+2+3) +1/4 (1+2+3+4) +...+ 1/16 (1+2+3+4+...+16)
A=1+1/2x3+1/3X6+1/4X10+...+1/16X136
A=1+3/2+2+5/2+3+...+17/2
A=2/2+3/2+4/2+5/2+6/2+...+17/2
A=2+3+4+5+...+16+17/2
A=(2+17)x16:2/2
A=19x16:2/2
A=304:2/2
A=152/2
A=76
****
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Tính P = 1+ 1/2(1+2) + 1/3(1+2+3) + 1/4(1+2+3+4)+...+1/16(1+2+3+...+16)
Tính:
A= 1 + 1/2. (1+2) +1/3. (1+2+3) +1/4. (1+2+3+4) + .............. + 1/16. (1+2+3+4+........+15+16)
Tính nhanh A = 1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/16(1+2+3+...+16)
tính nhanh A= 1+1/2(1+2) +1/3(1+2+3)+1/4(1+2+3+4)+...+ 1/16(1+2+3+...+16)
ta có
A = \(1+\frac{1+2}{2}+\frac{1+2+3}{3}+\frac{1+2+3+4}{4}+......+\frac{1+2+3+\text{4 +....+16}}{16}\)
xét tổng S = 1+2+3+4+5+......+n = \(\frac{\left(n+1\right)n}{2}\) lấy \(\frac{S}{n}=\frac{\frac{\left(n+1\right)n}{2}}{n}=\frac{n+1}{2}\)
ta có
A=\(1+\frac{\frac{2\left(2+1\right)}{2}}{2}+\frac{\frac{3\left(3+1\right)}{2}}{3}+\frac{\frac{4\left(4+1\right)}{2}}{4}+\frac{\frac{5\left(5+1\right)}{2}}{5}+......+\frac{\frac{16\left(16+1\right)}{2}}{16}\)
A = \(1+\frac{1+2}{2}+\frac{1+3}{2}+\frac{1+4}{2}+\frac{1+5}{2}+......+\frac{1+16}{2}\)
A = \(1+\frac{1+2+1+3+1+\text{4+1+5+1+6+.....+1+16}}{2}\)
A = \(1+\frac{151}{2}\)
A = \(\frac{153}{2}\)
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