Toán Lớp 6: A) 5.(12-x)+30=-20
B) 2.(x-51)=2.2^3+20
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Toán Lớp 6: A) 5.(12-x)+30=-20
B) 2.(x-51)=2.2^3+20
Comments ( 2 )
a)5.(12 – x) + 30 = -20
<=>5.(12 – x) = -20 – 30
<=>5.(12 – x) = -50
<=>12 – x = -50 : 5
<=>12 – x = -10
<=>x = 12 – (-10)
<=>x = 22
Vậy x = 22
b)2.(x – 51) = 2.2^{3} + 20
<=>2.(x – 51) = 2.8 + 20
<=>2.(x – 51) = 16 + 20
<=>2.(x – 51) = 36
<=>x – 51 = 36 : 2
<=>x – 51 = 18
<=>x = 51 + 18
<=>x = 69
Vậy x = 69
Giải đáp:
a) 22
b) 69
Lời giải và giải thích chi tiết:
a) 5 . ( 12 – x ) + 30 = – 20
=> 5 . ( 12 – x ) = – 20 – 30
=> 5 . ( 12 – x ) = – 50
=> 12 – x = (-50)/5
=> 12 – x = – 10
=> x = 12 + 10 = 22
Vậy x = 22
b) 2 . ( x – 51 ) = 2 . 2^3 + 20
=> 2 . ( x – 51 ) = 2 . 8 + 20
=> 2 . ( x – 51 ) = 16 + 20
=> 2 . ( x – 51 ) = 36
=> x – 51 = 36/2
=> x – 51 = 18
=> x = 18 + 51 = 69
Vậy x = 69