25% - (1)1/2 + 0,5 . 3/8
(0,5 điểm) Tính:
$\sqrt{25}.\left( 0,4-1\dfrac{1}{2} \right) : \left[ (-2)^3 : \dfrac{8}{11} \right]$.
\(\sqrt{25}.\left(0,4-1\dfrac{1}{2}\right):\left[\left(-2\right)^3:\dfrac{8}{11}\right]\)
\(=5.\left(\dfrac{2}{5}-\dfrac{3}{2}\right):\left(-8:\dfrac{8}{11}\right)\)
\(=5.\left(-\dfrac{11}{10}\right):\left(-11\right)\)
\(=\dfrac{-11}{2}:\left(-11\right)\)
\(=\dfrac{1}{2}\)
\(5\).\(\left(0,4-1,5\right):[-8:\dfrac{8}{11}]\)
=5.-11:-11
5
bài 1: thực hiện phép tính
A) 5/6 : -7/12
B) -21/24 : -14/8
c) 4/5 : -8/15
d) -15/16 . 8/-25
đ) 2/3 - 5/7 . 14/25
e)28/15.0,75 - ( 8/15 + 25%)
f) 0,75 - 43/80 : ( -4/5 + 2,5 . 3/4)
i) -5/8 . 5/12 + -5/8 . 7/12 + 17/8
0) 25% - 3/2 + 0,5 . 12/5
p) (-3,2) . -15/64+)0,8 - 34/15): 7/2
l) 75% - 3/2 + 0,5 : 5/12 - ( -1/2)mũ 2
giup mình với
mai nộp rồi
a: \(=\dfrac{5}{6}\cdot\dfrac{-12}{7}=\dfrac{-10}{7}\)
b: \(=\dfrac{7}{8}\cdot\dfrac{8}{14}=\dfrac{7}{14}=\dfrac{1}{2}\)
c: \(=\dfrac{4}{5}\cdot\dfrac{-15}{8}=\dfrac{-3}{2}\)
d: \(=\dfrac{15}{16}\cdot\dfrac{8}{25}=\dfrac{15}{25}\cdot\dfrac{1}{2}=\dfrac{3}{5}\cdot\dfrac{1}{2}=\dfrac{3}{10}\)
đ: \(=\dfrac{2}{3}-\dfrac{70}{175}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10-6}{15}=\dfrac{4}{15}\)
Tính
a) 0,5 x 8 + 2^3 x 1/4-2019^0
b)9x(-1/3)^2+1/3-2.(-1/2)^2-1/2(-1/2)^0
c)√25+√16/49-√(-3)^2
#Nguồn: Băng
a, \(0,5.8+2^3.\frac{1}{4}-2019^0\)
\(=\frac{1}{2}.8+8.\frac{1}{4}-1\)
\(=4+2-1\)
\(=5\)
b, \(9\left(-\frac{1}{3}\right)^2+\frac{1}{3}-2\left(-\frac{1}{2}\right)^2-\frac{1}{2}\left(\frac{1}{2}\right)^0\)
\(=9.\frac{1}{9}+\frac{1}{3}-2.\frac{1}{4}-\frac{1}{2}.1\)
\(=1+\frac{1}{3}-\frac{1}{2}-\frac{1}{2}\)
\(=\frac{1}{3}\)
c, \(\sqrt{25}+\frac{\sqrt{16}}{49}-\sqrt{\left(-3\right)^2}\)
\(=5+\frac{4}{49}-3\)
\(=\frac{42}{19}\)
x + x : 0,5 + x : 25% + x : 1/8 = 3
Ta có: x + x : 0,5 + x : 25% + x : 1/8 = 3
\(\Rightarrow\)\(x+x\times2+x\times4+x\times8=3\)
\(\Rightarrow\)x \(\times\)< 1 + 2 + 4 + 8 > \(=\) 3
\(\Rightarrow x\times15=3\)
\(\Rightarrow x=3\div15\)
\(\Rightarrow x=\frac{3}{15}\)
\(\Rightarrow x=\frac{1}{5}\)
Nhớ k chị nhé.
x+x.2+x.4+x.8=3
x.(1+2+4+8)=3
x.15=3
x=3:15
x=\(\frac{1}{5}\)
Thuc hien phep tinh:
a) 32.(-1/2)3+1/4
b) 16.(1/2)2.1/2
c) 17/22+4/25+29/25+0,5+5/22
d) 3/11-7/15+8/11-8/15+0.25
Cac ban ghi cac buoc lam gjum mik nha
bài 2 tìm x biết
4/5 . x = 8/35
3/5 x -1/2 = 1/7
x - 25 %x =0,5
( 1/24.25 + 1/25.26 + ...+1/29.30).120+ x : 1/3 = -4
\(a) \frac{4}{5}.x=\frac{8}{35}\)
\(\implies x= \frac{8}{35}:\frac{4}{5}\)
\(\implies x=\frac{8}{35}.\frac{5}{4}\)
\(\implies x=\frac{2}{7}\). Vậy \(x=\frac{2}{7}\)
\(b) \frac{3}{5}x-\frac{1}{2}=\frac{1}{7}\)
\(\implies \frac{3}{5}x=\frac{1}{7}+\frac{1}{2}\)
\(\implies \frac{3}{5}x=\frac{9}{14}\)
\(\implies x=\frac{9}{14}:\frac{3}{5}\)
\(\implies x=\frac{9}{14}.\frac{5}{3} \)
\(\implies x=\frac{15}{14}\). Vậy \(x=\frac{15}{14}\)
\(c) x-25\% x=0,5\)
\(\implies 75\% x=0,5\)
\(\implies \frac{3}{4}x=\frac{1}{2}\)
\(\implies x=\frac{1}{2}:\frac{3}{4}\)
\(\implies x=\frac{1}{2}.\frac{4}{3}\)
\(\implies x=\frac{2}{3}\). Vậy \(x=\frac{2}{3}\)
\(d) (\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}).120+x:\frac{1}{3}=-4\)
Có: \(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}\)
\(=\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}\)
\(=\frac{1}{24}-\frac{1}{30}\)
\(=\frac{1}{120}\)
Thay vào ta có: \(\frac{1}{120}.120+x:\frac{1}{3}=-4\)
\(\implies 1+x:\frac{1}{3}=-4\)
\(\implies x:\frac{1}{3}=-5\)
\(\implies x=-5.\frac{1}{3}\)
\(\implies x=\frac{-5}{3}\). Vậy \(x=\frac{-5}{3}\)
~ Hok tốt a~
\(\frac{4}{5}.x=\frac{8}{35}\) \(\frac{3}{5}x-\frac{1}{2}=\frac{1}{7}\)
\(x=\frac{8}{35}:\frac{4}{5}\) \(\frac{3}{5}x=\frac{1}{7}+\frac{1}{2}\)
\(x=\frac{8}{35}.\frac{5}{4}\) \(\frac{3}{5}x=\frac{9}{14}\)
\(x=\frac{2}{7}\) \(x=\frac{9}{14}:\frac{3}{5}\)
Vậy \(x=\frac{2}{7}\) \(x=\frac{9}{14}.\frac{5}{3}\)
\(x-25\%x=0.5\) \(x=\frac{15}{14}\)
\(x-\frac{1}{4}x=\frac{1}{2}\) Vậy \(x=\frac{15}{14}\)
\(x\left(1-\frac{1}{4}\right)=\frac{1}{2}\) \(\left(\frac{1}{24.25}+\frac{1}{25.26}+...+\frac{1}{29.30}\right).120+x:\frac{1}{3}=-4\)
\(x=\frac{1}{2}:\frac{3}{4}\) \(\left(\frac{1}{24}-\frac{1}{25}+\frac{1}{25}-\frac{1}{26}+...+\frac{1}{29}-\frac{1}{30}\right).120+x:\frac{1}{3}=-4\) \(x=\frac{2}{3}\) \(\left(\frac{1}{24}-\frac{1}{30}\right).120+x:\frac{1}{3}=-4\)
Vậy \(x=\frac{2}{3}\) \(\frac{1}{120}.120+x:\frac{1}{3}=-4\)
\(1+x:\frac{1}{3}=-4\)
\(x:\frac{1}{3}=\left(-4\right)-1\)
\(x:\frac{1}{3}=-5\)
\(x=\left(-5\right).\frac{1}{3}\)
\(x=-\frac{5}{3}\)
Vậy \(x=-\frac{5}{3}\)
1. Thực hiện phép tính bằng cách hợp lí nếu có thể:
a)140/27 + 7/23 + 0,5 - 5/27 + 16/23
b)3/8 * 135/5 - 256/5 * 3/8 + 19
c)25*(-1/5)3 +1/5 - 2 * (-1/2)2 -1/2
có một câu nữa : d)211/6 : (-4/5) - 271/6 : (-4/5)
a)13/2 b)9,925 c)-1 d)
a) (-1,25).17/21.(-0,4).7/34
b)0,5\(^{^{x+1}}\) + 0,5\(^x\) = 1,5
c) x:20-25%x=-1\(\dfrac{1}{5}\)
d) (x-1)\(^2\) =1
e) 5\(^3\) : 25+2\(^4\) :4
a: \(=\dfrac{5}{4}\cdot\dfrac{2}{5}\cdot\dfrac{17}{21}\cdot\dfrac{7}{34}=\dfrac{1}{2}\cdot\dfrac{1}{2}\cdot\dfrac{1}{3}=\dfrac{1}{12}\)
b: =>0,5^x(0,5+1)=1,5
=>0,5^x=1
=>x=0
c: =>x*0,05-0,25*x=-1,2
=>-0,3*x=-1,2
=>x=4
d: =>x-1=1 hoặc x-1=-1
=>x=0 hoặc x=2
e: =5+4=9
\(1\frac{13}{15}.\left(0,5\right)^2\)\(.|-3|+\left(\frac{8}{15}-25\%\right):1\frac{23}{24}\)
\(1\frac{13}{15}\cdot\left(0.5\right)^2\cdot\left|-3\right|+\left(\frac{8}{15}-25\%\right):1\frac{23}{24}\)
\(=\frac{28}{15}\cdot\frac{1}{4}\cdot3+\left(\frac{8}{15}-\frac{1}{4}\right)\cdot\frac{47}{24}\)
\(=\frac{28\cdot1\cdot3}{15\cdot4}+\frac{17}{60}\cdot\frac{47}{24}\)
\(=\frac{21}{25}+\frac{799}{1440}=\frac{10043}{7200}\)