a) 140 : (x - 8) = 7

x - 8 = 140 : 7

x - 8 = 20

x = 20 + 8

x = 28

b) 4(x + 41) = 400

x + 41 = 400 : 4

x + 41 = 100

x = 100 - 41

x = 59

c) 35 - 5(x + 4) = 35

5(x + 4) = 35 - 35

5(x + 4) = 0

x + 4 = 0

x = 0 - 4

x = -4

d) 25 + 3(x - 8)= 106

3(x - 8) = 106 - 25

3(x - 8) = 81

x - 8 = 81 : 3

x - 8 = 27

x = 27 + 8

x = 35

Bài 7: Ta có: \(a\cdot b=ƯCLN\left(a;b\right)\cdot BCN\mathbb{N}\left(a;b\right)\)

=>\(a\cdot b=10\cdot900=9000\)

ƯCLN(a;b)=10

=>a⋮10; b⋮10

ab=9000

mà a⋮10 và b⋮10 và a<b

nên (a;b)∈{(10;900);(20;450);(30;300);(50;180);(60;150);(90;100)}

mà ƯCLN(a;b)=10

nên (a;b)∈{(10;900);(20;450);(50;180);(90;100)}

Bài 5:

ƯCLN(a;b)=6

=>a⋮6; b⋮6

ab=216

mà a⋮6; b⋮6

nên (a;b)∈{(6;36);(12;18);(18;12);(36;6)}

Bài 4: Gọi hai số tự nhiên cần tìm là a,b

ƯCLN(a;b)=5

=>a⋮5; b⋮5

Ta có: ab=300

mà a⋮5; b⋮5

nên (a;b)∈{(5;60);(60;5);(10;30);(30;10);(15;20);(20;15)}

Bài 1:

a: ƯCLN(a;b)=6

=>a⋮6 và b⋮6

a+b=96

mà a⋮6 và b⋮6

nên (a;b)∈{(6;90);(90;6);(12;84);(84;12);(18;78);(78;18);(24;72);(72;24);(30;66);(66;30);(36;60);(60;36);(42;54);(54;42);(48;48)}

mà ƯCLN(a;b)=6

nên (a;b)∈{(6;90);(90;6);(18;78);(78;18);(30;66);(66;30);(42;54);(54;42)}

b: ƯCLN(a;b)=4

=>a⋮4 và b⋮4

a+b=16

mà a⋮4; b⋮4 và a>b

nên (a;b)∈{(12;4);(8;8)}

mà ƯCLN(a;b)=4

nên (a;b)=(12;4)

ngón tay gầy

Trả lời gúp mình với p

d: \(48\cdot26+24\cdot148\)

\(=48\cdot26+48\cdot74\)

\(=48\cdot\left(26+74\right)=48\cdot100=4800\)

e: \(23\cdot48+92\cdot88\)

\(=23\cdot4\cdot12+92\cdot88\)

\(=92\cdot12+92\cdot88=92\cdot100=9200\)

b: \(89\cdot25+89\cdot74+89\)

\(=89\cdot\left(25+74+1\right)\)

\(=89\cdot100=8900\)

Bài 5:

a: \(B=2009\cdot2011\)

\(=\left(2010-1\right)\left(2010+1\right)\)

\(=2010\cdot2010-1=A-1\)

=>B<A
b: \(B=2019\cdot2021\)

\(=\left(2020-1\right)\left(2020+1\right)\)

\(=2020\cdot2020-1\)

=A-1

=>B<A

c: \(A=234234\cdot233=234\cdot233\cdot1001\)

\(B=233233\cdot234=233\cdot234\cdot1001\)

Do đó: A=B

d: \(A=123\cdot137137=123\cdot137\cdot1001\)

\(B=137\cdot123123=137\cdot123\cdot1001\)

Do đó: A=B

Bài 4:

a: \(391-125<\overline{26x}<184+84\)

=>\(266<\overline{26x}<268\)

=>\(\overline{26x}=267\)

=>x=7

b: \(935+167<\overline{110x}<1240-135\)

=>\(1102<\overline{110x}<1105\)

=>x∈{3;4}

c: \(135\cdot12<\overline{162x}<4869:3\)

=>\(1620<\overline{162x}<1623\)

=>x∈{1;2}

d: \(11268:3<\overline{375x}<235\cdot16\)

=>\(3756<\overline{375x}<3760\)

=>x∈{7;8;9}

Bài 3:

l: x+125=492

=>x=492-125=367

m: 327-x=129

=>x=327-129=198

n: 124+(118-x)=217

=>118-x=217-124=93

=>x=118-93=25

o: 89-(73-x)=20

=>73-x=89-20=69

=>x=73-69=4

p: 198-(x+4)=120

=>x+4=198-120=78

=>x=78-4=74

q: (x+7)-25=23

=>x+7=25+23=48

=>x=48-7=41

r: 140:(x-8)=7

=>x-8=140:7=20

=>x=20+8=28

s: 4(x+41)=400

=>x+41=400:4=100

=>x=100-41=59

t: 4(3x-4)-2=18

=>4(3x-4)=2+18=20

=>3x-4=5

=>3x=9

=>x=3

u: 123-5(x+4)=38

=>5(x+4)=123-38=85

=>x+4=85:5=17

=>x=17-4=13

v: 231-(x-6)=1339:13

=>231-(x-6)=103

=>x-6=231-103=128

=>x=128+6=134

w: (x-36):18+12=14

=>(x-36):18=2

=>\(x-36=2\cdot18=36\)

=>x=36+36=72