Toán Lớp 6: a,11+(15-2x)=0
b,-129-(35-x)=55
c,27-2.5^5-2=5^8:5^6
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Toán Lớp 6: a,11+(15-2x)=0
b,-129-(35-x)=55
c,27-2.5^5-2=5^8:5^6
Comments ( 1 )
$a,$ $11+\left(15-2x\right)=0$
$⇒11+15-2x=0$
$⇒-2x+26=0$
$⇒-2x+26-26=0-26$
$⇒-2x=-26$
$⇒\dfrac{-2x}{-2}=\dfrac{-26}{-2}$
$⇒x=13$
Vậy $x=13$
$b,$ $-129-\left(35-x\right)=55$
$⇒-129-\left(35-x\right)+129=55+129$
$⇒-\left(35-x\right)=184$
$⇒\dfrac{-\left(35-x\right)}{-1}=\dfrac{184}{-1}$
$⇒35-x=-184$
$⇒35-x-35=-184-35$
$⇒-x=-219$
$⇒\dfrac{-x}{-1}=\dfrac{-219}{-1}$
$⇒x=219$
Vậy $x=219$
$c,$ $27-2\cdot 5^x-2=5^8:5^6$
$⇒5^x=0$
$⇒5^8:5^6=25$
Vậy không có giá trị x nào.