Toán Lớp 6: Tìm số nguyên x, biết:
a. x – 12 = – 28 b. 14x + 54 = 82 c. 95 – 5(x+2) = 45
d. 5(x + 12) + 22 = 92 e. 5 ( x – 3 ) = 15 f. 2x – 138 = 23 . 32
g. 10 + 2x = 45 : 4
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Toán Lớp 6: Tìm số nguyên x, biết:
a. x – 12 = – 28 b. 14x + 54 = 82 c. 95 – 5(x+2) = 45
d. 5(x + 12) + 22 = 92 e. 5 ( x – 3 ) = 15 f. 2x – 138 = 23 . 32
g. 10 + 2x = 45 : 4
Comments ( 1 )
Giải đáp:
$a) x-12=-28$
$⇒ x= (-28)+12$
$⇒ x= -16$
$vậy$ $x=-16$
$b) 14x+54=82$
$⇒ 14x= 82-54$
$⇒ 14x=28$
$⇒ x= 28:14$
$⇒ x=2$
$Vậy$ $x=2$
$c) 95-5.(x+2)=45$
$⇒ 5.(x+2)= 95-45$
$⇒ 5.(x+2)=50$
$⇒ x+2= 50:5$
$⇒ x+2=10$
$⇒ x=10-2$
$⇒ x=8$
$Vậy$ $x=8$
$d) 5.(x+12)+22=92$
$⇒ 5.(x+12)=92-22$
$⇒ 5.(x+12)=70$
$⇒ x+12= 70:5$
$⇒ x+12=14$
$⇒ x=14-12$
$⇒ x=2$
$Vậy$ $x=2$
$e) 5.(x-3)=15$
$⇒ x-3= 15:5$
$⇒ x-3=3$
$⇒ x= 3+3$
$⇒x=6$
$Vậy$ $x=6$
$f) 2x-138=23.32$
$⇒ 2x-138=736$
$⇒ 2x= 736+138$
$⇒ 2x=874$
$⇒ x= 437$
$vậy$ $x=437$
$g) 10+2x=45:4$
$⇒ 10+2x=11,25$
$⇒ 2x= 11,25-10$
$⇒ 2x=1,25$
$⇒ x=0,625$
$Vậy$ $x=0,625$