Toán Lớp 6: 1, (-12).(-8) = ?
2, 10² – [60:(5⁶:5⁴–3.5)]= ?
3, 5. (-17) = ?
4, (x+3).(x-5) = 0
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Toán Lớp 6: 1, (-12).(-8) = ?
2, 10² – [60:(5⁶:5⁴–3.5)]= ?
3, 5. (-17) = ?
4, (x+3).(x-5) = 0
Comments ( 2 )
$1,$ $\:\left(-12\right)\cdot \left(-8\right)\:$
$=12\cdot \:8$
$=96$
$2,$ $10²\:-\:\left[60:\left(5⁶:5⁴-3.5\right)\right]$
$=10^2-6$
$=100-6$
$=94$
$3,$ $5. (-17)$
$=-\left(5\cdot \:17\right)$
$=-85$
$4,$ $\left(x+3\right)\left(x-5\right)=0$
$⇒x+3=0\quad \mathrm{hoặc}\quad \:x-5=0$
\(⇒\left[ \begin{array}{l}x+3=0\\x-5=0\end{array} \right.\) \(⇒\left[ \begin{array}{l}x=-3\\x=5\end{array} \right.\)
$\text{Vậy x $\in$ (-3; 5)}$
Giải đáp+Lời giải và giải thích chi tiết:
1)
(-12).(-8)
=12.8
=96
2)
10^2-[60:(5^6 : 5^4-3.5)]
=100-[60 : (5^2-15)]
=100-[60 : (25-15)]
=100-(60 : 10)
=100-6
=94
3)
5.(-17)
=-(5.17)
=-85
4)
(x+3)(x-5)=0
<=> [(x+3=0),(x-5=0):}
<=> [(x=-3),(x=5):}
Vậy x \in {-3;5}