Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
12-|x|=8
=> |x|= 12-8= 4
=> x= 4 hoặc x= -4
T I C K cái nha, tí lm tiếp vài câu nữa, chờ tí
\(25:x^5-16=3^{15}:3^{13}\)
=>\(25:x^5-16=3^2=9\)
=>\(25:x^5=25\)
=>\(x^5=1\)
=>x=1
1) Ta có: \(\left(-\dfrac{2}{3}\right)^2\cdot\dfrac{-9}{8}-25\%\cdot\dfrac{-16}{5}\)
\(=\dfrac{4}{9}\cdot\dfrac{-9}{8}-\dfrac{1}{4}\cdot\dfrac{-16}{5}\)
\(=\dfrac{-1}{2}+\dfrac{4}{5}\)
\(=\dfrac{-5}{10}+\dfrac{8}{10}=\dfrac{3}{10}\)
2) Ta có: \(-1\dfrac{2}{5}\cdot75\%+\dfrac{-7}{5}\cdot25\%\)
\(=\dfrac{-7}{5}\cdot\dfrac{3}{4}+\dfrac{-7}{5}\cdot\dfrac{1}{4}\)
\(=\dfrac{-7}{5}\left(\dfrac{3}{4}+\dfrac{1}{4}\right)=-\dfrac{7}{5}\)
3) Ta có: \(-2\dfrac{3}{7}\cdot\left(-125\%\right)+\dfrac{-17}{7}\cdot25\%\)
\(=\dfrac{-17}{7}\cdot\dfrac{-5}{4}+\dfrac{-17}{7}\cdot\dfrac{1}{4}\)
\(=\dfrac{-17}{7}\cdot\left(\dfrac{-5}{4}+\dfrac{1}{4}\right)\)
\(=\dfrac{17}{7}\)
4) Ta có: \(\left(-2\right)^3\cdot\left(\dfrac{3}{4}\cdot0.25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
\(=\left(-8\right)\cdot\left(\dfrac{3}{4}\cdot\dfrac{1}{4}\right):\left(\dfrac{9}{4}-\dfrac{7}{6}\right)\)
\(=\left(-8\right)\cdot\dfrac{3}{16}:\dfrac{54-28}{24}\)
\(=\dfrac{-3}{2}\cdot\dfrac{24}{26}\)
\(=\dfrac{-72}{52}=\dfrac{-18}{13}\)
Ta có: \(\left(\dfrac{-2}{3}\right)\cdot\dfrac{-9}{8}-25\%\cdot\dfrac{-16}{5}\)
\(=\dfrac{18}{24}-\dfrac{1}{4}\cdot\dfrac{-16}{5}\)
\(=\dfrac{3}{4}+\dfrac{4}{5}\)
\(=\dfrac{15}{20}+\dfrac{16}{20}=\dfrac{31}{20}\)
Bài 3 .
a.25.(-70).2.(-4)
=[25.(-4)].[(-70).2]
=(-100).(-140)
=14000
b.16.(12-6)-12.(16-6)
=(16.12-16.6)-(12.16-12.6)
=16.12-16.6-12.16+12.6
=(16.12-12.16)-(16.6-12.6)
=0-6.(16-12)
=0-24=-24
c.125.(-24)+24.255
=24.[(-125)+255]
=24.100
=2400
d)25.(-55)+(-25).45
=25.[(-55)+(-45)]
=25.(-100)
=-2500
Bài 4
a.3x+18=3
3x =3-18
3x =-15
x =-15:3
x =-5
Vậy x=-5
b)\(4\left|x\right|=16\)
\(\left|x\right|\)=16:4
\(\left|x\right|\)=4
⇒\(\left[{}\begin{matrix}x=-4\\x=4\end{matrix}\right.\)
Vậy x∈{-4;4}
3)a)=(25.2).[(-70).(-4)]
=50.(-280)
=-14000
b)=16.6-12.10
=96-120
=-24
c)=-3000+6120
=3120
d)=1375+-1125
=250
4)a) 3x=3-18
3x=-15
x=-15:3
x=-5
b) \x\=16:4
\x\=4
suy ra x=4;-4
125(28+72)-25(3^2.4+64)
=125.100-25(9.4+64)
=125.100-25.(36+64)
=125.100-25.100
=12500-2500
=10000
x.3 - 25 = -16
x.3 = -16 + 25
x.3 = 9
x= 9:3
x=3