Toán Lớp 6: a)x-2-(12-23)=4 ; b)42-(x-21)=56; c) 13-(2.x-5)=24 ; d)2.x-(4)=7 ;e) 36:(2.x-1)^2=45
giúp mình với , nhanh lên nhé
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Toán Lớp 6: a)x-2-(12-23)=4 ; b)42-(x-21)=56; c) 13-(2.x-5)=24 ; d)2.x-(4)=7 ;e) 36:(2.x-1)^2=45
giúp mình với , nhanh lên nhé
Comments ( 2 )
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a) x-2-(12-23)=4
x-2-(-11)=4
x-2+11=4
x-2=4-11
x-2=-7
x=-7+2
x=-5
b) 42-(x-21)=56
x-21=42-56
x-21=-14
x=-14+21
x=7
c) 13-(2x-5)=24
2x-5=13-24
2x-5=-11
2x=-11+5
2x=-6
x=-6:2
x=-3
d) 2x-4=7
2x=7+4
2x=11
x=11:2
x=5,5
Giải đáp:
$\text{a/ x = -5 ; b/ x = 7; c/ x = -3}$
Lời giải và giải thích chi tiết:
$\text{a/ x – 2 – (12 – 23) = 4}$
$\text{⇔ x – 2 – 12 + 23 = 4}$
$\text{⇔ x – (2 + 12 – 23) = 4}$
$\text{⇔ x – (-9) = 4}$
$\text{⇔ x = 4 – 9}$
$\text{⇒ x = -5}$
$\text{b/ 42 – (x – 21) = 56}$
$\text{⇔ 42 – x + 21 = 56}$
$\text{⇔ (42 – 21) – x = 56}$
$\text{⇔ 63 – x = 56}$
$\text{⇔ x = 63 – 56}$
$\text{⇒ x = 7}$
$\text{c/ 13 – (2x – 5) = 24}$
$\text{⇔ 2x – 5 = 13 – 24}$
$\text{⇔ 2x – 5 = -11}$
$\text{⇔ 2x = -11 + 5}$
$\text{⇔ 2x = -6}$
$\text{⇔ x = -6 : 2}$
$\text{⇒ x = -3}$
$\text{d/ 2x – 4 = 7}$
$\text{⇔ 2x = 4 + 7}$
$\text{⇔ 2x = 11}$
$\text{⇔ x = 11 : 2}$
$\text{⇒ x = 5,5}$