Bài 1: Cho a và b là hai số nguyên tố cùng nhau chứng minh rằng:
a. (a , a - b) = 1
b. (ab , a + b) = 1
Bài 2: Tìm hai số tự nhiên a và b biết tích của chúng là 2940 và BCNN của chúng là 210
Bài 3: Tìm hai số a và b, biết tổng của BCNN với UWCLN của chúng là 15
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a) goi hai so la a ; b va a >b
vi UCLN(a,b)=18=>a=18k ; b=18q (trong do UCLN (k,q)=1 va k>q)
=>a+b=162
18k+18q =162
18(k+q)=162
k+q=9
ta co bang sau | |||||||||||||||||||||||
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21453
52542000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 | 542454550212.100000000000000000000000000000000000000000000000000000000000000000000000000000 |
Vào đây http://olm.vn/hoi-dap/question/89869.html
ƯCLN(a;b)=2940:210=14
vậy a=14m ; b=14n (m\(\ge\)n)
thay vào a.b=2940 ta được
14m=14n=2940
=>m.n=2904:(14.14)=15
vì m\(\ge\)n nên 15=5.3=15.1
với m=5; n=3 thì a=70; b=42
với m=15; n=1 thì a=210; b=1
a,a là gì vậy bạn
Mình cũng chả biết :v