Toán Lớp 6: Tìm x
a) 2x + 7 = 15
b) 25 – 3(6 – x) = 22
c) (25- 2x)3 : 5 – 32 = 42
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Toán Lớp 6: Tìm x
a) 2x + 7 = 15
b) 25 – 3(6 – x) = 22
c) (25- 2x)3 : 5 – 32 = 42
Comments ( 2 )
.
a ) 2x + 7 = 15
=> 2x = 15 – 7
=> 2x = 8
=> x = 8 : 2
=> x = 4
Vậy x = 4
b ) 25 – 3(6 – x) = 22
=> 3(6 – x) = 25 – 22
=> 3(6 – x) = 3
=> 6 – x = 3 : 3
=> 6 – x = 1
=> x = 6 – 1
=> x = 5
Vậy x = 5
c ) ( 25 – 2x ) 3 : 5 – 32 = 42
=> ( 25 – 2x ) 3 : 5 = 42 + 32
=> (25 – 2x ) 3 : 5 = 74
=> ( 25 – 2x ) 3 = 74 .5
=> ( 25 – 2x) 3 = 370
=> 25 – 2x = 370 : 3
=> 25 – 2x = 370/3
=> 2x = 25 – 370/3
=> 2x = -295/3
=> x = -295/3 :2
=> x = -295/6
Vậy x = -295/6
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