Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Gọi 4 số lẻ lần lượt là
a+1;a+3;a+5;a+7
đề => (a+5)(a+7)-(a+1)(a+3)=160
=> a(a+7)+5(a+7)-a(a+3)-a-3=160
=>aa+7a+5a+35-aa-3a-3-a=160
=>8a+32=160
=>a=16
=>dãy=17:19:21;23
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 | |||||||||||||||||||||||
vay ........... | |||||||||||||||||||||||
21453
52542000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 | 542454550212.100000000000000000000000000000000000000000000000000000000000000000000000000000 |
Tổng tất cả các số tự nhiên nằm giữa a và b là 280
=>Số số hạng của dãy số là:
(b-1)-(a+1)+1=b-1-a-1+1=b-a-1(số)
Tổng của dãy số là: \(\left(b-1+a+1\right)\cdot\frac{\left(b-a-1\right)}{2}=\frac{\left(b+a\right)\left(b-a-1\right)}{2}\)
Theo đề, ta có: \(\left(b+a\right)\left(b-a-1\right)=280\cdot2=560\)
TH1: a=2; b=3
(b+a)(b-a-1)
\(=\left(3+2\right)\cdot\left(3-2-1\right)=0\)
=>Loại
=>a,b phải là hai số nguyên tố lẻ
=>b+a chẵn và b-a chẵn
=>b-a-1 lẻ
(b+a)(b-a-1)=560
mà b+a chẵn; b-a-1 lẻ
nên (b+a;b-a-1)∈{(560;1);(112;5);(80;7);(35;16)}
TH1: b+a=560 và b-a-1=1
=>b+a=560 và b-a=2
=>b=(560+2)/2=562/2=281; a=281-2=279⋮3
=>Loại
TH2: b+a=112 và b-a-1=5
=>b+a=112 và b-a=6
=>b=(112+6)/2=59; a=112-59=53
=>Nhận
TH3: b+a=80 và b-a-1=7
=>b+a=80 và b-a=8
=>b=(80+8)/2=44⋮4
=>loại
TH4: b+a=35 và b-a-1=16
=>b+a=35 và b-a=17
=>b=(35+17)/2=52/2=26⋮2
=>Loại
Vậy: a=53; b=59
T=a+b
=53+59
=112