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a) \(\left(+5\right).\left(+11\right)=\left(+55\right)\)
b) \(\left(-6\right).9=\left(-54\right)\)
c) \(3.\left(-7\right)=\left(-21\right)\)
d) \(\left(-250\right).\left(-8\right)=\left(+2000\right)\)
e) \(\left(+4\right).\left(-3\right)=\left(-12\right)\)
1. A = (-2)(-3) - 5.|-5| + 125.\(\left(-\dfrac{1}{5}\right)^2\)
= 6 - 25 + 125.\(\dfrac{1}{25}\)
= -19 + 5
= -14
@Shine Anna
a) ( − 3 ) . ( − 4 ) . ( − 5 )=-60
b) ( − 5 + 8 ) . ( − 7 )=-21
c) (−6−3).(−6+3)(−6−3).(−6+3)=27
d) (−4−14):(−3)=6
a) \(\left(-3\right).\left(-4\right)\left(-5\right)\) = \(12.\left(-5\right)\) = \(-60\)
b) \(\left(-5+8\right).\left(-7\right)\) = \(3.\left(-7\right)\) = \(-21\)
c) \(\left(-6-3\right).\left(-6+3\right)\) = \(-9.\left(-3\right)\) = 27
d) \(\left(-4-14\right):\left(-3\right)\) = \(-18:\left(-3\right)\) = 6
a,|x|+3=5
\(\Leftrightarrow\left|x\right|=5-3=2\)
\(\Rightarrow x=\left\{{}\begin{matrix}2\\-2\end{matrix}\right.\)
b,|x+3|=5
\(\Rightarrow\left\{{}\begin{matrix}x+3=5\\x+3=-5\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}2\\-8\end{matrix}\right.\)
c,|x-7|+13=25
<=>|x-7|=25-13=12
\(\Rightarrow\left\{{}\begin{matrix}x-7=12\\x-7=-12\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=19\\x=-5\end{matrix}\right.\)
d,\(26-\left|x+9\right|=-13\)
\(\Leftrightarrow\left|x+9\right|=26-\left(-13\right)=39\)
\(\Rightarrow\left\{{}\begin{matrix}x+9=39\\x+9=-39\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=30\\x=-48\end{matrix}\right.\)
e,8-|x|=15
<=>|x|=8-15=-7
\(\Rightarrow\left\{{}\begin{matrix}x=-7\\x=7\end{matrix}\right.\)
f,6-|-3+x|=-15
\(\Leftrightarrow\left|-3+x\right|=6-\left(-15\right)=21\)
\(\Rightarrow\left\{{}\begin{matrix}-3+x=21\\-3+x=-21\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=24\\x=-18\end{matrix}\right.\)
a, |x| + 3 = 5
|x| = 5 - 3
|x| = 2
|x| = 2 hoặc |x| = -2
Vậy |x| thuộc {2; -2}
b,|x + 3| = 5
|x + 3| = 5 hoặc |x + 3| = -5
x = 5 - 3 x = (-5) - 3
x = 2 x = -8
Vậy x thuộc {2; -8}
c,|x - 7| + 13 = 25
|x - 7| = 25 - 13
|x - 7| = 12
|x - 7| = 12 hoặc |x - 7| = -12
x = 12 + 7 x = (-12) + 7
x = 19 x = -5
Vậy x thuộc {19 ; -5}
a) (−4).(−5).(−6)= 20.(-6)= -120
b) (−3+6).(−4)= 3.(-4)= -12
c) (−3−5)(−3+5)= -8. 2 = -16
d) (−5−13):(−6)= -18:( -6)= 3
a) \(2\left(x-5\right)-3\left(x+7\right)=14\)
\(\Leftrightarrow2x-10-3x-21=14\)
\(\Leftrightarrow-x-31=14\)
\(\Leftrightarrow-x=45\Leftrightarrow x=-45\)
b) \(5\left(x-6\right)-2\left(x+3\right)=12\)
\(\Leftrightarrow5x-30-2x-6=12\)
\(\Leftrightarrow3x-36=12\)
\(\Leftrightarrow3x=48\Leftrightarrow x=16\)
c) \(3\left(x-4\right)-\left(8-x\right)=12\)
\(\Leftrightarrow3x-12-8+x=12\)
\(\Leftrightarrow4x-20=12\)
\(\Leftrightarrow4x=32\Leftrightarrow x=8\)
d) \(-7\left(3x-5\right)+2\left(7x-14\right)=28\)
\(\Leftrightarrow-21x+35+14x-28=28\)
\(\Leftrightarrow-7x+35=0\Leftrightarrow x=5\)
a) 27; b) -21; c) -65; d) 600; e) -35.
Sách Giáo Khoa
Tính:
a) (+3) . (+9); b) (-3) . 7; c) 13 . (-5);
d) (-150) . (-4); e) (+7) . (-5).
Bài giải:
a) 27; b) -21; c) -65; d) 600; e) -35.