Câu 1: Tìm số tự nhiên x, biết:
a) 7x - 8 =713
b) 2448 : [119 - (x-6)] =24
c)2016 -100.(x+11) = 2^7:2^3
Câu 2:Kết quả phép tính : 879.2+879.996+3.879
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\(a,2448:\left[119-\left(x-6\right)\right]=24\)
\(119-\left(x-6\right)=2448:24\)
\(119-\left(x-6\right)=102\)
\(x-6=119-102\)
\(x-6=17\)
\(x=17+6\)
\(\Rightarrow x=23\)
\(b,2016-100\times\left(x+11\right)=128:8\)
\(2016-100\times\left(x+11\right)=16\)
\(100\times\left(x+11\right)=2016-16\)
\(100\times\left(x+11\right)=2000\)
\(x+11=2000:100\)
\(x+11=20\)
\(x=20-11\)
\(\Rightarrow x=9\)
\(a,2448:\left[119-\left(x-6\right)\right]=24\\ 119-\left(x-6\right)=2448:24\\ 119-\left(x-6\right)=102\\ x-6=119-102\\ x-6=17\\ x=17+6\\ x=23\\ b,2016-100\times\left(x+11\right)=128:8\\ 2016-100\times\left(x+11\right)=16\\ 100\times\left(x+11\right)=2016-16\\ 100\times\left(x+11\right)=2000\\ x+11=2000:100\\ x+11=20\\ x=20-11\\ x=9\)
\(2448:\left[119-\left(x-6\right)\right]=24\)
\(119-\left(x-6\right)=2448:24\)
\(119-\left(x-6\right)=102\)
\(x-6=119-102\)
\(x-6=17\)
\(x=17+6\)
\(x=23\)( thỏa mãn \(x\in N\) )
vậy x = 23
\(2016-100\cdot\left(x+11\right)=2^7:2^3\)
\(2016-100\cdot\left(x+11\right)=128:8\)
\(2016-100\cdot\left(x+11\right)=16\)
\(100\cdot\left(x+11\right)=2016-16\)
\(100\cdot\left(x+11\right)=2000\)
\(x+11=2000:100\)
\(x+11=20\)
\(x=20-11\)
\(x=9\)( thỏa mãn \(x\in N\))
vậy x = 9
bài 2
a) 2448:[119-(x-6)]=24
119-(x-6)=2448:24
119-(x-6)=102
x-6=119-102
x-6=17
x=17+6
x=23
Câu b,
= 50x + (1 + 3 + 5 + ..... + 99) = 2550
= 50x + 2500 = 2550
= 50x = 2550 - 2500
= 50x = 50
= x = 50 : 50
= x = 1
a: Ta có: \(7x+25=144\)
\(\Leftrightarrow7x=119\)
hay x=17
b: Ta có: \(33-12x=9\)
\(\Leftrightarrow12x=24\)
hay x=2
c: Ta có: \(128-3\left(x+4\right)=23\)
\(\Leftrightarrow3\left(x+4\right)=105\)
\(\Leftrightarrow x+4=35\)
hay x=31
d: Ta có: \(71+\left(726-3x\right)\cdot5=2246\)
\(\Leftrightarrow5\left(726-3x\right)=2175\)
\(\Leftrightarrow726-3x=435\)
\(\Leftrightarrow3x=291\)
hay x=97
e: Ta có: \(720:\left[41-\left(2x+5\right)\right]=40\)
\(\Leftrightarrow41-\left(2x+5\right)=18\)
\(\Leftrightarrow2x+5=23\)
\(\Leftrightarrow2x=18\)
hay x=9
Câu 1 :
a) 7x-8=713
7x=713+8
7x=721
x=721:7
x=103
Vậy x=103.
b)2448:[119-(x-6)]=24
119-(x-6)=2448:24
119-(x-6)=102
x-6=119-102
x-6=17
x=17+6
x=23
Vậy x=23.
c) 2016-100(x+11)=27:23
2016-100(x+11)=24=16
100(x+11)=2016-16
100(x+11)=2000
x+11=2000:100
x+11=20
x=20-11
x=9
Vậy x=9.
Câu 2 :
879.2+879.996+3.879=879(2+996+3)
=879.1001
=879879