Tính:
a, 5/9 + 2/3 =
b, 7/8 x 5/7 =
c, 6/5 : 2/3 =
d, 7/2 - 29/14 =
a) 5/9+ 6/9= 11/9
b) 5/8
c) 6/5 x 3/2 = 9/5
d) 49/14- 29/14= 20/14 = 10/7
a, 5/9 + 2/3 = 11/9
b, 7/8 x 5/7 = 5/8
c, 6/5 : 2/3 = 9/5
d, 7/2 - 29/14 =10/7
1. Thực hiện phép tính:
a) -1/3 + 7/6 b) 5/7 - 3/5 c) 0,75 . 4/5
2. Tìm x:
a) 4/5 + x = 2/3 b) 1/2 - x = 7/12 c) 3 và 1/2 : x = -7/2 d) 3/8 - 1/6 x =5/2
e) x + 50%x = -1,5
3. Lớp 6H có 40 học sinh gồm 3 loại: giỏi, khá và trung bình. Biết số học sinh giỏi chiếm 1/5 số học sinh cả lớp. Số học sinh còn lại gồm khá và trung bình. Số học sinh trung bình bằng 3/8 số học sinh còn lại.
Hỏi lớp 6H có bao nhiêu học sinh xếp loại giỏi, khá và trung bình?
3: Số học sinh giỏi là 40*1/5=8 bạn
Số học sinh trung bình là 32*3/8=12 bạn
Số học sinh khá là 32-12=20 bạn
1:
a: -1/3+7/6=7/6-2/6=5/6
b: 5/7-3/5=25/35-21/35=4/35
c: 0,75*4/5=4/5*3/4=3/5
a) 16 - 18/x| = -8 -14|x|
b) 5 x|+7.(2/x|-3) =4.(x-4)+25
e) 15-3|4x +2| = 3 8) 18 -4.(6-2|x|) = - 3.(4|x|+5)+29
8) 27-5/x -10 = 4|x-10| - 18
h) 510 + 3x|-21 = 7- 2|15+3x|
c) 43x +2|-16= 20
d) 8|x - 1|-4 = 12+6|x-1|
giúp em với
Tính:
a) 6/7 + 7/8 b) 4/5 - 2/3 c) 2/3 x 4/9 d) 1/5 : 2/7
a) \(\dfrac{6}{7}+\dfrac{7}{8}=\dfrac{48}{56}+\dfrac{49}{56}=\dfrac{97}{56}\)
b) \(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\)
c) \(\dfrac{2}{3}.\dfrac{4}{9}=\dfrac{8}{27}\)
d) \(\dfrac{1}{5}:\dfrac{2}{7}=\dfrac{1}{5}.\dfrac{7}{2}=\dfrac{7}{10}\)
a: =48/56+49/56
=97/56
b: =12/15-10/15
=2/15
c: =(2*4)/(3*9)=8/27
d: =1/5*7/2=7/10
` 6/7 + 7/8 = 48/56 + 49/56 = 97/56`
` 4/5 - 2/3 = 12/15 - 10/15 = 2/15`
` 2/3 xx 4/9 = 8/27`
` 1/5 : 2/7 = 1/5 . 7/2 = 7/10`
Bài1:Thực hiện phép tính:
a,(2^4.3.5^2):{450:[450-(4.5^3-2^3.5^2)]}
b,3^3.5^2-20{90-[164-2.(7^8:7^6+7^0)]}
c,[(18^7:18^6-17).2022-1986].5.1^2022-13^2.2020^0
Bài2:Tìm x:
a,(2^x+1)^2+3.(2^2+1)=2^2.10
b,3.(x-7)+2.(x+5)=41
(GIÚP MIK VỚI Ạ)
Bài 1.
\(a,\left(2^4\cdot3\cdot5^2\right):\left\{450:\left[450-\left(4\cdot5^3-2^3\cdot5^2\right)\right]\right\}\)
\(=\left(16\cdot3\cdot25\right):\left\{450:\left[450- \left(4\cdot125-8\cdot25\right)\right]\right\}\)
\(=\left(48\cdot25\right):\left\{450:\left[450-\left(500-200\right)\right]\right\}\)
\(=1200:\left[450:\left(450-300\right)\right]\)
\(=1200:\left(450:150\right)\)
\(=1200:3\)
\(=400\)
\(---\)
\(b,3^3\cdot5^2-20\left\{90-\left[164-2\cdot\left(7^8:7^6+7^0\right)\right]\right\}\)
\(=27\cdot25-20\left\{90-\left[164-2\cdot\left(7^2+1\right)\right]\right\}\)
\(=675-20\left\{90-\left[164-2\cdot\left(49+1\right)\right]\right\}\)
\(=675-20\left[90-\left(164-2\cdot50\right)\right]\)
\(=675-20\left[90-\left(164-100\right)\right]\)
\(=675-20\left(90-64\right)\)
\(=675-20\cdot26\)
\(=675-520\)
\(=155\)
\(---\)
\(c,\left[\left(18^7:18^6-17\right)\cdot2022-1986\right]\cdot5\cdot1^{2022}-13^2\cdot2020^0\)
\(=\left[\left(18-17\right)\cdot2022-1986\right]\cdot5\cdot1-169\cdot1\)
\(=\left(1\cdot2022-1986\right)\cdot5-169\)
\(=\left(2022-1986\right)\cdot5-169\)
\(=36\cdot5-169\)
\(=180-169\)
\(=11\)
Bài 2.
\(a) (2^x+1)^2+3\cdot(2^2+1)=2^2\cdot10\\\Rightarrow (2^x+1)^2+3\cdot(4+1)=4\cdot10\\\Rightarrow (2^x+1)^2+3\cdot5=40\\\Rightarrow (2^x+1)^2+15=40\\\Rightarrow (2^x+1)^2=40-15\\\Rightarrow (2^x+1)^2=25\\\Rightarrow (2^x+1)^2= (\pm 5)^2\\\Rightarrow \left[\begin{array}{} 2^x+1=5\\ 2^x+1=-5 \end{array} \right.\\ \Rightarrow \left[\begin{array}{} 2^x=4\\ 2^x=-6 (vô.lí) \end{array} \right. \\ \Rightarrow 2^x=2^2\\\Rightarrow x=2\)
Vậy \(x=2\).
\(---\)
\(b)3\cdot(x-7)+2\cdot(x+5)=41\\\Rightarrow 3\cdot x+3\cdot(-7)+2\cdot x+2\cdot5=41\\\Rightarrow 3x-21+2x+10=41\\\Rightarrow (3x+2x)+(-21+10)=41\\\Rightarrow 5x-11=41\\\Rightarrow 5x=41+11\\\Rightarrow 5x=52\\\Rightarrow x=\dfrac{52}{5}\)
Vậy \(x=\dfrac{52}{5}\).
\(Toru\)
1.Tính:
a) 2/7 + 5/3 b) 49 + 5(số 5 ở giữa dòng)
c)4/7 x 5/8 d) ¼ x 5/6 x 7/3
2.Tính bằng 2 cách
a. ( 3/5 + ½) x 4/5 a. ( 3/5 + ½) x 4/5
b. 2/5 x 3/7 + 2/5 x 4/7 b. 2/5 x 3/7 + 2/5 x 4/7
3. Tìm x:
X + 3/8 = 14/9 x 10/35 x – 2/7= 21/10 x 15/28
11/7 – x = 8/3 x 9/32 2/5 + x = 12/35 x 14/9
Bài 3:
a: x+3/8=14/9x10/35
\(\Leftrightarrow x+\dfrac{3}{8}=\dfrac{4}{9}\)
=>x=4/9-3/8=32/72-27/72=5/72
b: \(x-\dfrac{2}{7}=\dfrac{21}{10}\cdot\dfrac{15}{28}=\dfrac{21}{28}\cdot\dfrac{15}{10}=\dfrac{3}{4}\cdot\dfrac{3}{2}=\dfrac{9}{8}\)
\(\Leftrightarrow x=\dfrac{9}{8}+\dfrac{2}{7}=\dfrac{63}{56}+\dfrac{16}{56}=\dfrac{79}{56}\)
c: \(\dfrac{11}{7}-x=\dfrac{8}{3}\cdot\dfrac{9}{32}=\dfrac{1}{4}\cdot3=\dfrac{3}{4}\)
nên \(x=\dfrac{11}{7}-\dfrac{3}{4}=\dfrac{44}{28}-\dfrac{21}{28}=\dfrac{23}{28}\)
d: \(x+\dfrac{2}{5}=\dfrac{12}{35}\cdot\dfrac{14}{9}=\dfrac{4}{3}\cdot\dfrac{2}{5}=\dfrac{8}{15}\)
nên \(x=\dfrac{8}{15}-\dfrac{2}{5}=\dfrac{8}{15}-\dfrac{10}{15}=-\dfrac{2}{15}\)
Giải các pt sau:
A, x+3/2 - x-1/3 = x+5/6 + 1
B, x+1/35 + x+3/33 = x+5/31 + x+7/29
C, x-10/18 + x-8/20 + x-6/22 = x-19/9 + x-21/7 + x-15/13
A, \(\frac{x+3}{2}\)-\(\frac{x-1}{3}\)=\(\frac{x+5}{6}\)+1
⇔ \(\frac{3\left(x+3\right)}{6}\)-\(\frac{2\left(x-1\right)}{6}\)=\(\frac{x+5}{6}\)+\(\frac{6}{6}\)
⇔ 3x+9-2x+2=x+5+6
⇔ 3x-2x-x=5+6-9-2
⇔0x=0 (luôn đúng với mọi x)
Vậy phương trình có vô số nghiêm:S=R
a) \(x+\frac{3}{2}-x-\frac{1}{3}=x+\frac{5}{6}+1\)
⇔ \(\frac{3}{2}-x-\frac{1}{3}=\frac{5}{6}+1\)
⇔ \(\frac{7}{6}-x=\frac{5}{6}+1\)
⇔ \(\frac{7}{6}-x=\frac{11}{6}\)
⇔ \(-x=\frac{11}{6}-\frac{7}{6}\)
⇔ \(-x=\frac{2}{3}\)
⇔ \(x=\frac{-2}{3}\)
Vậy tập nghiệm của pt là S = \(\left\{\frac{-2}{3}\right\}\)
Tính:
a) \(\dfrac{11}{10}+\dfrac{3}{5}:\dfrac{2}{3}\)
b) \(\dfrac{4}{3}\) + 5 x \(\dfrac{5}{8}\)
c) \(\left(\dfrac{2}{5}+\dfrac{3}{7}\right)x\dfrac{25}{29}\)
d) \(\dfrac{1}{4}x\dfrac{5}{12}+\dfrac{5}{12}x\dfrac{4}{5}\)
a) \(\dfrac{11}{10}+\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{11}{10}+\dfrac{3}{5}\times\dfrac{3}{2}=\dfrac{11}{10}+\dfrac{9}{10}=\dfrac{20}{10}=2\)
b) \(\dfrac{4}{3}+5\times\dfrac{5}{8}=\dfrac{4}{3}+\dfrac{25}{8}=\dfrac{32}{24}+\dfrac{75}{24}=\dfrac{107}{24}\)
c) \(\left(\dfrac{2}{5}+\dfrac{3}{7}\right)\times\dfrac{25}{29}=\left(\dfrac{14}{35}+\dfrac{15}{35}\right)\times\dfrac{25}{39}=\dfrac{29}{35}\times\dfrac{25}{39}=\dfrac{145}{274}\)
d) \(\dfrac{1}{4}\times\dfrac{5}{12}+\dfrac{5}{12}\times\dfrac{4}{5}=\dfrac{5}{12}\times\left(\dfrac{1}{4}+\dfrac{4}{5}\right)=\dfrac{5}{12}\times\dfrac{21}{20}=\dfrac{105}{240}=\dfrac{7}{16}\)
a) \(\dfrac{11}{10}+\dfrac{3}{5}x\dfrac{3}{2}=\dfrac{11}{10}+\dfrac{9}{10}=\dfrac{20}{10}=2\)
b) \(\dfrac{4}{3}+\dfrac{25}{8}=\dfrac{32}{24}+\dfrac{75}{24}=\dfrac{107}{24}\)
c) \(\dfrac{29}{35}x\dfrac{25}{29}=\dfrac{5}{7}\)
\(=\dfrac{5}{12}x\left(\dfrac{1}{4}+\dfrac{4}{5}\right)=\dfrac{5}{12}x\dfrac{21}{20}=\dfrac{7}{16}\)
tìm x biết
a) 7-(18+x)=-15
b) (x-17)-(-3)=0
c)-18-(x-6)=0
d) 29-(10+29)=x-(27-9)
a,\(7-\left(18+x\right)=-15\)
\(18+x=7-\left(-15\right)\)
\(18+x=22\)
\(x=4\)
b,\(\left(x-17\right)-\left(-3\right)=0\)
\(x-17=-3\)
\(x=14\)
c,\(-18-\left(x-6\right)=0\)
\(x-6=-18\)
\(x=-12\)
d,\(29-\left(10+29\right)=x-\left(27-9\right)\)
\(x-18=-10\)
\(x=8\)
a) \(7-\left(18+x\right)=-15\)
\(\Leftrightarrow18+x=7+15\)
\(\Leftrightarrow18+x=22\)
\(\Leftrightarrow x=22-18\)
\(\Leftrightarrow x=4\)
b) \(\left(x-17\right)-\left(-3\right)=0\)
\(\Leftrightarrow\left(x-17\right)+3=0\)
\(\Leftrightarrow x-17=0-3\)
\(\Leftrightarrow x-17=-3\)
\(\Leftrightarrow x=-3+17\)
\(\Leftrightarrow x=14\)
c) \(-18-\left(x-6\right)=0\)
\(\Leftrightarrow x-6=0+\left(-18\right)\)
\(\Leftrightarrow x-6=-18\)
\(\Leftrightarrow x=-18+6\)
\(\Leftrightarrow x=-12\)
d) \(29-\left(10+29\right)=x-\left(27-9\right)\)
\(\Leftrightarrow29-10-29=x-27+9\)
\(\Leftrightarrow-10=x-27+9\)
\(\Leftrightarrow x-27=-10-9\)
\(\Leftrightarrow x-27=-19\)
\(\Leftrightarrow x=-19+27\)
\(\Leftrightarrow x=8\)
a)
7 - (18 + x) = -15
18 + x = 7 - ( -15 )
18 + x = 7 + 15
18 + x = 22
x = 22 - 18
x = 4
b)
(x - 17) - (-3) = 0
x - 17 = 0 + -3
x - 17 = -3
x = -3 + 17
x = 14
c)
-18 - (x - 6) = 0
x - 6 = -18 - 0
x - 6 = -18
x = -18 + 6
x = -12
d)
29 - (10 + 29) = x - (27 - 9)
29 - 39 = x - 18
x - 18 = -10
x = -10 + 18
x = 8
