(x-7) . (x+3)<0
nho ghi cach giai dum nha
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Tính nhẩm:
7 x 2 =
4 x 7 =
7 x 6 =
3 x 7 =
5 x 7 =
2 x 7 =
7 x 4 =
6 x 7 =
7 x 3 =
7 x 5 =
7 x 2 = 14
4 x 7 = 28
7 x 6 = 42
3 x 7 = 21
5 x 7 = 35
2 x 7 = 14
7 x 4 = 28
6 x 7 = 42
7 x 3 = 21
7 x 5 = 35
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7 x 2 = 14
4 x 7 = 28
7 x 6 = 42
3 x 7 = 21
5 x 7 = 35
2 x 7 = 14
7 x 4 = 28
6 x 7 = 42
7 x 3 = 21
7 x 5 = 35
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7 x 2 = ..... 7 x 4 = ..... 7 x 6 = ..... 7 x 3 = .....
2 x 7 = ..... 4 x 7 = ..... 6 x 7 = ..... 3 x 7 = .....
14 : 7 = ..... 28 : 7 = ..... 42 : 7 = ..... 21 : 7 = .....
14 : 2 = ..... 28 : 4 = ..... 42 : 6 = ..... 21 : 3 = .....
7 x 2 = 14 7 x 4 = 28 7 x 6 = 42 7 x 3 = 21
2 x 7 = 14 4 x 7 = 28 6 x 7 = 42 3 x 7 = 21
14 : 7 = 2 28 : 7 = 4 42 : 7 = 6 21 : 7 = 3
14 : 2 = 7 28 : 4 = 7 42 : 6 = 7 21 : 3 = 7
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Viết số thích hợp vào ô trống:7 x 2 2 x 6 x 7 7 x 3 x 7 x 37 x 5 5 x 4 x 7 7 x 7 x 0 x 7
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Viết số thích hợp vào ô trống:
7 x 2 = 2 x 
6 x 7 = 7 x 
3 x 7 = 
x 3
7 x 5 = 5 x 
4 x 7 = 7 x 
7 x 0 = 
x 7
7 x 2 = 2 x [7] 6 x 7 = 7 x [6] 3 x 7 = [7] x 3
7 x 5 = 5 x [7] 4 x 7 = 7 x [4] 7 x 0 = [0] x 7
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2\(^7\) + ( x - 3\(^7\) ) = 5\(^7\) - 4\(^7\)
3 \(^x\) - (x + 2 \(^x\)) = 7
7 \(^2\) - (15 + x) = 5.2 \(^2\)
7 \(^3\) - 7(13 - x) = 14
a: \(2^7+\left(x-3^7\right)=5^7-4^7\)
=>\(128+x-2187=78125-16384\)
=>\(x-2059=61741\)
=>\(x=61741+2059=63800\)
c: \(7^2-\left(x+15\right)=5\cdot2^2\)
=>49-(x+15)=5*4=20
=>x+15=29
=>x=14
d: 7^3-7(13-x)=14
=>343-7(13-x)=14
=>7(13-x)=343-14=329
=>13-x=47
=>x=13-47=-34
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Viết số thích hợp vào chỗ chấm :
7 x 3 = ... 7 x 1 = ... 7 x 6 = ... 7 x 0 = ...
3 x 7 = ... 1 x 7 = ... 6 x 7 = ... 7 x 7 = ...
7 x 3 = 21 7 x 1 = 7 7 x 6 = 42 7 x 0 = 0
3 x 7 = 21 1 x 7 = 7 6 x 7 = 42 7 x 7 = 49
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1) x+1/2=-5/3
2) 1/3-x=3/5
4) x-4/3=-7/9
5) x--7/3=5/6
6) x-1/5=9/10
7) x+5/12=3/8
8) x+5/4=7/6
9) x-2/7=1/35
10) x-2/7=-7/10
6: =>x=9/10+1/5=9/10+2/10=11/10
7: =>x=3/8-5/12=36/96-40/96=-1/24
8: =>x=7/6-5/4=14/12-15/12=-1/12
9: =>x=1/35+2/7=1/35+10/35=11/35
10: =>x=2/7-7/10=20/70-49/70=-29/70
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1, \(x=-\dfrac{5}{3}-\dfrac{1}{2}=-\dfrac{10}{6}-\dfrac{3}{6}=-\dfrac{13}{6}\)
2, \(x=\dfrac{1}{3}-\dfrac{3}{5}=\dfrac{5-9}{15}=-\dfrac{4}{15}\)
4, \(x=-\dfrac{7}{9}+\dfrac{4}{3}=\dfrac{-7+12}{9}=\dfrac{5}{9}\)
5, \(x=\dfrac{5}{6}-\dfrac{7}{3}=\dfrac{5-14}{6}=-\dfrac{9}{6}=-\dfrac{3}{2}\)
6, \(x=\dfrac{9}{10}+\dfrac{1}{5}=\dfrac{9+2}{10}=\dfrac{11}{10}\)
7, \(x=\dfrac{3}{8}-\dfrac{5}{12}=\dfrac{9-10}{12}=-\dfrac{1}{12}\)
8, \(x=\dfrac{7}{6}-\dfrac{5}{4}=\dfrac{14-15}{12}=-\dfrac{1}{12}\)
9, \(x=\dfrac{1}{35}+\dfrac{2}{7}=\dfrac{1+10}{35}=\dfrac{11}{35}\)
10, \(x=-\dfrac{7}{10}+\dfrac{2}{7}=\dfrac{-49+20}{70}=\dfrac{-29}{70}\)
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X-7 = -5 (x+2) = 0 (3x - 24) . 73 =2.74 | x - 5 | = |-7| x- [42 + ( -28) = -8 ( 7x - x ) - ( 25+7 ) = -25 |x-3| = |5| + | -7 | ( x : 3-4 ) : 5 =15 | x -3 | = 7 - (-2) 128 -3 . (x+4) = 23 4 - ( 7-x ) = x - (13-4 ) BÀI 2 : TÍNH NHANH S1 = 1+2+3+.......999 S1= 10 +12 + 14 +.......2010 S3 + 21 + 23 + 25 + .......10001
1/ x + 1/2 = -5/3 6/ x - 1/5 = 9/10
2/ 1/3 - x = 3/5 7/ x + 5/12 = 3/8
3/ 3-4 + x = 7/2 8/ x + 5/4 = 7/6
4/ x - 4/3 = -7/9 9/ x - 2/7 = 1/35
5/ x - -7/3 = 5/6 10/ x - 1/5 = -7/10
\(1,\\ x+\dfrac{1}{2}=-\dfrac{5}{3}\\ x=-\dfrac{5}{3}-\dfrac{1}{2}\\ x=-\dfrac{13}{6}\\ Vậyx=-\dfrac{13}{6}\)
\(2,\\ \dfrac{1}{3}-x=\dfrac{3}{5}\\ x=\dfrac{1}{3}-\dfrac{3}{5}\\ x=-\dfrac{4}{15}\\ Vậyx=-\dfrac{4}{15}\)
\(3,\\ 3-4+x=\dfrac{7}{2}\\ -1+x=\dfrac{7}{2}\\ x=\dfrac{7}{2}+1\\ x=\dfrac{9}{2}\\ Vậyx=\dfrac{9}{2}\)
\(4,\\ x-\dfrac{4}{3}=-\dfrac{7}{9}\\ x=-\dfrac{7}{9}+\dfrac{4}{3}\\ x=\dfrac{15}{27}\\ Vậyx=\dfrac{15}{27}\)
\(5,\\ x-\left(-\dfrac{7}{3}\right)=\dfrac{5}{6}\\ x=\dfrac{5}{6}-\dfrac{7}{3}\\ x=-\dfrac{27}{18}\\ Vậyx=-\dfrac{27}{18}\)
\(6,\\ x-\dfrac{1}{5}=\dfrac{9}{10}\\ x=\dfrac{9}{10}+\dfrac{1}{5}\\ x=\dfrac{11}{10}\\ Vậyx=\dfrac{11}{10}\)
\(7,\\ x+\dfrac{5}{12}=\dfrac{3}{8}\\ x=\dfrac{3}{8}-\dfrac{5}{12}\\ x=-\dfrac{1}{24}\\ Vậyx=-\dfrac{1}{24}\)
\(8,\\ x+\dfrac{5}{4}=\dfrac{7}{6}\\ x=\dfrac{7}{6}-\dfrac{5}{4}\\ x=-\dfrac{9}{24}\\ Vậyx=-\dfrac{9}{24}\)
\(9,\\ x-\dfrac{2}{7}=\dfrac{1}{35}\\ x=\dfrac{1}{35}+\dfrac{2}{7}\\ x=\dfrac{11}{35}\\ Vậyx=\dfrac{11}{35}\\ 10,\\ x-\dfrac{1}{5}=-\dfrac{7}{10}\\ x=-\dfrac{7}{10}+\dfrac{1}{5}\\ x=-\dfrac{1}{2}\\ Vậyx=-\dfrac{1}{2}\)
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Tìm x biết
1) 2.(x +5)+3.(x+7)41. 6) 7. (x -1)+5.(3-x)11.x-10
2) 5. ( x +6 ) +2.(x-3)38. 7) 4. (2+x)+3(x-2)12
3) 7.(5+x)+2.(x-10)15. 8) 5. ( 2+x) +4.(3-x)10x-15
4) 3. (x+4)+(8-2.x) 22. 9) 7.(x-2) +5.(3-x)11x-6
5) 4. (x+5)+3.(7-x)49. 10) 5.(3-x)+5.(x+4)6+4x
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Tìm x biết
1) 2.(x +5)+3.(x+7)=41. 6) 7. (x -1)+5.(3-x)=11.x-10
2) 5. ( x +6 ) +2.(x-3)=38. 7) 4. (2+x)+3(x-2)=12
3) 7.(5+x)+2.(x-10)=15. 8) 5. ( 2+x) +4.(3-x)=10x-15
4) 3. (x+4)+(8-2.x) =22. 9) 7.(x-2) +5.(3-x)=11x-6
5) 4. (x+5)+3.(7-x)=49. 10) 5.(3-x)+5.(x+4)=6+4x
1) 2(x + 5) + 3(x + 7) = 41
2x + 10 + 3x + 21 = 41
5x + 31 = 41
5x = 10
x = 2
6) 7(x - 1) + 5(3 - x) = 11x - 10
7x - 7 + 15 - 5x = 11x - 10
2x + 8 = 11x - 10
-9x = -18
x = 2
2) 5(x + 6) + 2(x - 3) = 38
5x + 30 + 2x - 6 = 38
7x + 24 = 38
7x = 14
x = 2
7) 4(2 + x) + 3(x - 2) = 12
8 + 4x + 3x - 6 = 12
7x + 2 = 12
7x = 10
x = 10/7
3) 7(5 + x) + 2(x - 10) = 15
35 + 7x + 2x - 20 = 15
9x + 15 = 15
9x = 0
x = 0
8) 5(2 + x) + 4(3 - x) = 10x - 15
10 + 5x + 12 - 4x = 10x - 15
x + 22 = 10x - 15
9x = 37
x = 37/9
4) 3(x + 4) + (8 - 2x) = 22
3x + 12 + 8 - 2x = 22
x + 20 = 22
x = 2
9) 7(x - 2) + 5(3 - x) = 11x - 6
7x - 14 + 15 - 5x = 11x - 6
2x + 1 = 11x - 6
-9x = -7
x = 7/9
5) 4(x + 5) + 3(7 - x) = 49
4x + 20 + 21 - 3x = 49
x + 41 = 49
x = 8
10) 5(3 - x) + 5(x + 4) = 6 + 4x
15 - 5x + 5x + 20 = 6 + 4x
35 = 6 + 4x
4x = 29
x = 29/4
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1) 2(x + 5) + 3(x + 7) = 41
2x + 10 + 3x + 21 = 41
5x + 31 = 41
5x = 41 - 31
5x = 10
x = 10 : 5
x = 2
2) 5(x + 6) + 2(x - 3) = 38
5x + 30 + 2x - 6 = 38
7x + 24 = 38
7x = 38 - 24
7x = 14
x = 14 : 7
x = 2
3) 7(5 + x) + 2(x - 10) = 15
35 + 7x + 2x - 20 = 15
9x + 15 = 15
9x = 15 - 15
9x = 0
x = 0
4) 3(x + 4) + (8 - 2x) = 22
3x + 12 + 8 - 2x = 22
x + 20 = 22
x = 22 - 20
x = 2
5) 4(x + 5) + 3(7 - x) = 49
4x + 20 + 21 - 3x = 49
x + 41 = 49
x = 49 - 41
x = 8
6) 7(x - 1) + 5(3 - x) = 11x - 10
7x - 7 + 15 - 5x = 11x - 10
2x - 11x + 8 = -10
-9x = -10 - 8
-9x = -18
x = -18 : (-9)
x = 2
7) 4(2 + x) + 3(x - 2) = 12
8 + 4x + 3x - 6 = 12
7x + 2 = 12
7x = 12 - 2
7x = 10
x = 10/7
8) 5(2 + x) + 4(3 - x) = 10x - 15
10 + 5x + 12 - 4x = 10x - 15
10x - 15 = x + 22
10x - x = 22 + 15
9x = 37
x = 37/9
9) 7(x - 2) + 5(3 - x) = 11x - 6
7x - 14 + 15 - 5x = 11x - 6
11x - 6 = 2x + 1
11x - 2x = 1 + 6
9x = 7
x = 7/9
10) 5(3 - x) + 5(x + 4) = 6 + 4x
15 - 5x + 5x + 20 = 6 + 4x
6 + 4x = 35
4x = 35 - 6
4x = 29
x = 29/4
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tìm x thuộc Z biết:
1) 2(4x-8)-7(3+x)=[-4](3-2)
2) 12(x-4)+6(x-2)-16(x+3)=7[-4]
3) 4(x-5)-7(5-x)+10(5-x)=-3
4) -3[x+5]=15(-3)+7(-3)
5) 4[x-7]-3(-5)=-2[x-7]-10
1) <=> 8x-16-21-7x=-4
<=> x-37=-4
<=> x=33
2) <=> 12x-48+6x-12-16x-48=-28
<=> 2x-108=-28
<=> 2x = 80
<=> x = 40
3)<=> 4x-20-35+7x+50-10x=-3
<=> x-5=-3
<=> x=2
4) <=> -3x-15=-45-21
<=> 51=3x
<=> 17=x
5) 4x-28+15=-2x+14-10
<=> 6x-13=4
<=> 6x=17
<=> x = \(\frac{17}{6}\)
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