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Bài 6:
\(max_{x-y}=max_x-min_y=11-\left(-89\right)=100\\ min_{x-y}=min_x-max_y=-2-1=-3\)
Bài 7:
\(\Leftrightarrow2\left(a+b+c\right)=11-3-2=6\\ \Leftrightarrow a+b+c=3\\ \Leftrightarrow\left\{{}\begin{matrix}a=3-\left(b+c\right)=6\\b=11-a=5\\c=-3-b=-8\end{matrix}\right.\)
Bài 7:
Ta có:
\(\left(a+b\right)+\left(b+c\right)+\left(a+c\right)=11+\left(-3\right)+\left(-2\right)\\ \Rightarrow2\left(a+b+c\right)=6\\ \Rightarrow a+b+c=3\)
\(\Rightarrow\left\{{}\begin{matrix}a=\left(a+b+c\right)-\left(b+c\right)=3-\left(-3\right)=6\\b=\left(a+b+c\right)-\left(a+c\right)=3-\left(-2\right)=5\\c=\left(a+b+c\right)-\left(a+b\right)=3-11=-8\end{matrix}\right.\)
Bài 4:
a: \(\Leftrightarrow n-1\in\left\{1;-1;5;-5\right\}\)
hay \(n\in\left\{2;0;6;-4\right\}\)
Bài 2:
a. $=124-52.124+124.47=124(1-52+47)=124(48-52)=124.(-4)=-496$
b. $=55(-78)+13(-78)-65(-78)=(-78)(55+13-65)=(-78).3=-234$
c. $=100(-47)+53(-100)=100(-47)+(-53).100=100[(-47)+(-53)]=100.(-100)=-10000$
d. $=25.75-25.49.3-75.25+75.49$
$=25.75-49.75-75.25+75.49=(25.75-75.25)+(75.49-49.75)=0+0=0$
Bài 3:
a. Ta nhớ quy tắc âm * âm = dương nên:
$(-18)(-13)>0$
$(-15)(-17)>0$
$\Rightarrow (-18)(-13)> (-15)(-17)$ (đpcm)
b.
$(-1)(-2)>0$
$(-3)(-4)>0$
$.....$
$(-17)(-18)>0$
$-19<0$
$\Rightarrow (-1)(-2)...(-18)(-19)<0$
Bài 2
a)-7<x<6
x=-6;-5;-4;-3;-2;-1;0;1;2;3;4;5.
b)4>x>-5
x=3;2;1;0;-1;-2;-3;-4
c: \(\Leftrightarrow n+2\in\left\{1;-1;5;-5\right\}\)
hay \(n\in\left\{-1;-3;3;-7\right\}\)
d: \(\Leftrightarrow n+2\in\left\{1;-1;2;-2;4;-4\right\}\)
hay \(n\in\left\{-1;-3;0;-4;2;-6\right\}\)
a: \(\Leftrightarrow n-1\in\left\{1;-1;5;-5\right\}\)
hay \(n\in\left\{2;0;6;-4\right\}\)
a: =100x54-100x(-6)
=100x60
=6000
b: =99(123-56+66-123)=990
c: =547x(1+103-4)=54700
d: =-76x10=-760
#)Giải :
\(A=\frac{72^3.54^2}{104^4}=\frac{72^3.54^2}{\left(54.2\right)^4}=\frac{72^3.54^2}{54^4.2^4}=\frac{72^3}{54^2.2^4}=\frac{3^5.2^6}{3^5.2^6}=1\)