a, 5\24 + x= 7\12
b, x - 3\4=1\2
c, (2\7.x+3\7) :2 1\5-3\7=1
ai giúp minh với
a, 5\24 + x= 7\12
b, x - 3\4=1\2
c, (2\7.x+3\7) :2 1\5-3\7=1
ai giúp minh với nha
a) \(\dfrac{5}{24}+x=\dfrac{7}{12}\)
<=> \(x=\dfrac{7}{12}-\dfrac{5}{24}=\dfrac{14}{24}-\dfrac{5}{24}=\dfrac{9}{24}=\dfrac{3}{8}\)
b) \(x-\dfrac{3}{4}=\dfrac{1}{2}\)
<=> \(x=\dfrac{1}{2}+\dfrac{3}{4}=\dfrac{2}{4}+\dfrac{3}{4}=\dfrac{5}{4}\)
c) bn ghi rõ đề chút
ok bạn
(2\7.x+3\7) :2 1\5-3\7=1
hai phần bảy nhân x cộng ba phần bảy chia hai một phần năm trừ 3 phần bảy bằng một
Giải:
a) \(\dfrac{5}{24}+x=\dfrac{7}{12}\)
\(x=\dfrac{7}{12}-\dfrac{5}{24}\)
\(x=\dfrac{3}{8}\)
b) \(x-\dfrac{3}{4}=\dfrac{1}{2}\)
\(x=\dfrac{1}{2}+\dfrac{3}{4}\)
\(x=\dfrac{5}{4}\)
c) \(\left(\dfrac{2}{7}.x+\dfrac{3}{7}\right):2\dfrac{1}{5}-\dfrac{3}{7}=1\)
\(\left(\dfrac{2}{7}.x+\dfrac{3}{7}\right):\dfrac{11}{5}=1+\dfrac{3}{7}\)
\(\left(\dfrac{2}{7}.x+\dfrac{3}{7}\right):\dfrac{11}{5}=\dfrac{10}{7}\)
\(\dfrac{2}{7}.x+\dfrac{3}{7}=\dfrac{10}{7}.\dfrac{11}{5}\)
\(\dfrac{2}{7}.x+\dfrac{3}{7}=\dfrac{22}{7}\)
\(\dfrac{2}{7}.x=\dfrac{22}{7}-\dfrac{3}{7}\)
\(\dfrac{2}{7}.x=\dfrac{19}{7}\)
\(x=\dfrac{19}{7}:\dfrac{2}{7}\)
\(x=\dfrac{19}{2}\)
4.Tính giá trị của biểu thức bằng cách thuận tiện:
a. 5 x 9 x 7 x 4 x 18 / 3 x 6 x 7 x 45 x 12
b. 1/10 x 2/9 x 3/8 x 4/7 x 5/6 x 6/5 x 7/4 x 8/3 x 9/2
c.14/15 x 27/35 x 25/22 x 44/9
5.Một con sên phải bò lên đỉnh cái cột, giờ thứ nhất, sên bò được 1/5 cái cột, giờ thứ 2 bò được 1/6 cái cột. Hỏi sau 2 giờ con sên còn phải bò bao nhiêu phần cái cột nữa?
Bài 2:
Sau 2 giờ con ốc sên bò được:
1/5+1/6=11/30(cây cột)
Sau 2 giờ thì con ốc sên còn phải bò:
1-11/30=19/30(cây cột)
1.Tìm số tự nhiên x biết 1) (x-35) -120=0 2) 310-(118-x) =217 3) 156-(x+61)=82 4) 814-(x-305)=712 5) 100-7-(x-5)=58 6) 12(x-1):3=4^3+2^3 7) 24+5x=7^5:7^3 8) 5.(x-1) :3=4^3+2^3 9) 5(x-4)^2-7=13 10) (x+1)+(x+2)+....(x+30)=795 Giúp em với Mai em đi học rồi Help
1) (x - 35) - 120 = 0
x - 35 = 120
x = 120 + 35
x = 155
2) 310 - (118 - x) = 217
118 - x = 310 - 217
118 - x = 93
x = 118 - 93
x = 25
3) 156 - (x + 61) = 82
x + 61 = 156 - 82
x + 61 = 74
x = 74 - 61
x = 13
4) 814 - (x - 305) = 712
x - 305 = 814 - 712
x - 305 = 102
x = 102 + 305 = 407
5) 100 - 7 - (x - 5) = 58
x - 5 = 93 - 58
x - 5 = 35
x = 35 + 5 = 40
6) 12(x - 1) : 3 = 43 + 23
4(x - 1) = 72
x - 1 = 18
x = 18 + 1 = 19
7) 24 + 5x = 75 : 73
24 + 5x = 49
5x = 25
x = 25 : 5 = 5
8) 5(x - 1) : 3 = 43 + 23
\(\dfrac{5}{3}\left(x-1\right)=72\)
x - 1 = \(\dfrac{216}{5}\)
x = 221/5
9) 5(x - 4)2 - 7 = 13
5(x - 4)2 = 20
(x - 4)2 = 4
\(\Rightarrow\left[{}\begin{matrix}x-4=2\\x-4=-2\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=6\\x=2\end{matrix}\right.\)
10) (x + 1) + (x + 2) + ... + (x + 30) = 795
=> (x + x + x + ... + x) + (1 + 2 + 3 +...+ 30) = 795 (1)
Đặt A = 1 + 2 + 3 +...+ 30
Số số hạng trong A là: (30 - 1) : 1 + 1 = 30 (số)
Tổng A bằng : (30 + 1).30 : 2 =465
Thay A = 465 vào (1) , ta được:
30x + 465 = 795
=> 30x =330
=> x =11
1: =>x-35=120
=>x=120+35=155
2: =>118-x=310-217=93
=>x=118-93=25
3: =>x+61=156-82=74
=>x=74-61=13
4: =>x-305=814-712=102
=>x=102+305=407
5: =>93-(x-5)=58
=>x-5=35
=>x=40
6: =>4(x-1)=64+8=72
=>x-1=18
=>x=19
7: =>5x+24=49
=>5x=25
=>x=5
8: =>5(x-1):3=4^3+2^3=64+8=72
=>5(x-1)=216
=>x-1=216/5
=>x=221/5
a)2x^3+x^2-4x-12
b)x^5-xy^4+x^4y-y^5
c) (x+1)(x+3)(x+5)(x+7)-9
\(2x^3+x^2-4x-12\)
\(=2x^3+5x^2+6x-4x^2-10x-12\)
\(=\left(2x^3+5x^2+6x\right)-\left(4x^2+10x+12\right)\)
\(=x\left(2x^2+5x+6\right)-2\left(2x^2+5x+6\right)\)
\(=\left(x-2\right)\left(2x^2+5x+6\right)\)
\(a,2x^3+x^2-4x-12=\left(2x^3-4x^2\right)+\left(5x^2-10x\right)+\left(6x-12\right)=2x^2\left(x-2\right)+5x\left(x-2\right)+6\left(x-2\right)=\left(x-2\right)\left(2x^2+5x+6\right)\)
\(b,x^5-xy^4+x^4y-y^5=x\left(x^4-y^4\right)+y\left(x^4-y^4\right)=\left(x+y\right)\left(x^4-y^4\right)=\left(x+y\right)\left(x^2-y^2\right)\left(x^2+y^2\right)=\left(x+y\right)^2\left(x-y\right)\left(x^2+y^2\right)\)
\(c,\left(x+1\right)\left(x+3\right)\left(x+5\right)\left(x+7\right)-9=\left[\left(x+1\right)\left(x+7\right)\right]\left[\left(x+3\right)\left(x+5\right)\right]-9=\left(x^2+8x+7\right)\left(x^2+8x+15\right)-9\)
đặt \(x^2+8x+11=y\)
\(\left(x^2+8x+7\right)\left(x^2+8x+15\right)-9=\left(y-4\right)\left(y+4\right)-9=y^2-16-9=y^2-25=\left(y-5\right)\left(y+5\right)=\left(x^2+8x+11-5\right)\left(x^2+8x+11+5\right)=\left(x^2+8x+6\right)\left(x^2+8x+16\right)=\left(x^2+8x+6\right)\left(x+4\right)^2\)
bài 9:tìm x
1) (x-3)^2-4=0
2) x^2-2x=24
3) (2x-1)^2+(x+3)^3-5(x+7)(x-7)=0
giúp mình với mn ơi
1) \(\left(x-3\right)^2-4=0\)
\(\Leftrightarrow\left(x-3-2\right)\left(x-3+2\right)=0\)
\(\Leftrightarrow\left(x-5\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=1\end{matrix}\right.\)
2) \(x^2-2x=24\)
\(\Leftrightarrow x^2-2x-24=0\)
\(\Leftrightarrow x^2+4x-6x-24=0\)
\(\Leftrightarrow x\left(x+4\right)-6\left(x+4\right)=0\)
\(\Leftrightarrow\left(x+4\right)\left(x-6\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\)
Tìm x biết
a,2/3.x+1/3=1/5
b,4/5- 5/3.x=-2
c,1/5+5/3:x=1/2
d,5/7:x-3=-2/7
a \(\dfrac{2}{3}x+\dfrac{1}{3}=\dfrac{1}{5}\\ \dfrac{2}{3}x=\dfrac{1}{5}-\dfrac{1}{3}\\ \dfrac{2}{3}x=\dfrac{-2}{15}\\ x=-\dfrac{2}{15}:\dfrac{2}{3}\\ x=-\dfrac{1}{5}\) b) \(\dfrac{4}{5}-\dfrac{5}{3}x=-2\\ \dfrac{5}{3}x=\dfrac{4}{5}+2\\ \dfrac{5}{3}x=\dfrac{14}{5}\\ x=\dfrac{14}{5}:\dfrac{5}{3}\\ x=\dfrac{42}{25}\)c) \(\dfrac{1}{5}+\dfrac{5}{3}:x=\dfrac{1}{2}\\ \dfrac{5}{3}:x=\dfrac{1}{2}-\dfrac{1}{5}\\ \dfrac{5}{3}:x=\dfrac{3}{10}\\ x=\dfrac{5}{3}:\dfrac{3}{10}\\ x=\dfrac{50}{9}\)d) \(\dfrac{5}{7}:x-3=-\dfrac{2}{7}\\ \dfrac{5}{7}:x=3-\dfrac{2}{7}\\ \dfrac{5}{7}:x=\dfrac{19}{7}\\ x=\dfrac{5}{7}:\dfrac{19}{7}\\ x=\dfrac{5}{19}\)
1/ 10(X-7)-8(X+5)=6(-5)+24
2/ 8(X-|-7|)-6(X-2)=|-8|.6-50
3/ 2(4X-8)-7(3+X)=|-4|(3-2)
4/ 12(X-4)=6(x-2)-16(X+3)=7|-4|
5/ 4(X-5)-7(5-X)+10(5-X)=-3
bn nào giải giúp mik vs nha:)))
1/ 10(X-7)-8(X+5)=6(-5)+24
10x - 70 - 8x - 40 = -30 +24
2x - 110 = -6
2x = 104
x=52
2/ 8(X-|-7|)-6(X-2)=|-8|.6-50
8(x - 7) - 6(x-2) = 8.6 - 50
8x - 56 - 6x +12 =48 -50
2x - 44 = -2
2x = 42
x=21
3/ 2(4X-8)-7(3+X)=|-4|(3-2)
8x-16 - 21 - 7x = 4.1
x-37=4
x=41
4/ 12(X-4)=6(x-2)-16(X+3)=7|-4|
12x - 48 = 6x - 12 - 16x -48 =7.4
12x - 48 = 28
12x=76
x=19/3
5/ 4(X-5)-7(5-X)+10(5-X)=-3
4x - 20 -35 +7x + 50 -10x = -3
x - 5 = -3
x = -2
Chúc bạn học tốt!
a,7/4+-3/5
b,2021-(1/3)^2 x 3^2
c,7,5 x(-3/5)
d,(-1/4)^2 x 4/11+7/11 x(-1/4)^2
e, A= 1/4 +1/4^2+1/4^3+...+1/4^2020<1/3
a: \(\dfrac{7}{4}+\dfrac{-3}{5}=\dfrac{35-12}{20}=\dfrac{23}{20}\)
d: \(\left(-\dfrac{1}{4}\right)^2\cdot\dfrac{4}{11}+\dfrac{7}{11}\cdot\left(-\dfrac{1}{4}\right)^2=\dfrac{1}{16}\)
\(\dfrac{7}{4}+\dfrac{-3}{5}=\dfrac{35}{20}+\dfrac{-12}{20}=\dfrac{23}{20}\)
bài 1 tìm x biết: a 3/8. x = 9/8 -1 b 4/5 . x = 7/5 - 1/5 c 12/7 : x + 2/3 = 7/5 d 3. (x +7) - 15 = 27 giúp mik với
a) 3/8 . x = 9/8 - 1
3/8 . x = 1/8
x = 1/8 : 3/8
x = 1/3
b) 4/5 . x = 7/5 - 1/5
4/5 . x = 6/5
x = 6/5 : 4/5
x = 3/2
c) 12/7 : x + 2/3 = 7/5
12/7 : x = 7/5 - 2/3
12/7 : x = 11/15
x = 12/7 : 11/15
x = 180/77
d) 3.(x + 7) - 15 = 27
3.(x + 7) = 27 + 15
3.(x + 7) = 42
x + 7 = 42 : 3
x + 7 = 14
x = 14 - 7
x = 7
a) \(\dfrac{3}{8}x=\dfrac{9}{8}-1\)
\(\Rightarrow\dfrac{3}{8}x=\dfrac{1}{8}\)
\(\Rightarrow x=\dfrac{1}{8}:\dfrac{3}{8}=\dfrac{1}{3}\)
b) \(\dfrac{4}{5}x=\dfrac{7}{5}-\dfrac{1}{5}\)
\(\Rightarrow\dfrac{4}{5}x=\dfrac{6}{5}\)
\(\Rightarrow x=\dfrac{6}{5}:\dfrac{4}{5}=\dfrac{3}{2}\)
c) \(\dfrac{12}{7}:x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{11}{15}\)
\(\Rightarrow x=\dfrac{12}{7}:\dfrac{11}{15}=\dfrac{180}{77}\)
d) \(3\left(x+7\right)-15=27\)
\(\Leftrightarrow3\left(x+7\right)=42\)
\(\Leftrightarrow x+7=14\Leftrightarrow x=7\)