cho bieu thuc:P= 2n+1/n-3 + 3n-5/n-3 + 4n-5/n-3
a) tim n de P nhan gia tri nguyen
b)tim n de P la phan so toi gian
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cho bieu thuc :A=2n+1/n-3+3n-5/n-3-4n-5/n-3.a, tim n de a nhan gia tri nguyen .b,tim n de a la phan so toi gian
cho bieu thuc :A=2n+1/n-3+3n-5/n-3-4n-5/n-3.a, tim n de a nhan gia tri nguyen .b,tim n de a la phan so toi gian
1) Cho bieu thuc : A= 2n +1 /n-3 + 3n-5/ n-3 - 4n-5 /n-3
a)Tim so nguyen n de A nhan gia tri nguyen
b) Tim n de A la phan so toi gian
Tim so tu nhien n de phan so A=\(\frac{2n+1}{n-3}+\frac{3n-5}{n-3}-\frac{4n-5}{n-3}\)
a/Tim n de A nhan gia tri nguyen
b/Tim n de A la phan so toi gian
bai 1
a, chung to rang 2n+5/n+3, ( n thuoc N ) la phan so toi gian
b, tim gia tri nguyen cua n de B= 2n+5/n+3 co gia tri la so nguyen
bai 2
tim so tu nhien nho nhat sao khi chia cho 3 du 1 cho 4 du 2 cho 5 du 3 cho 6 du 4 va chia het cho 11
\(a;\frac{2n+5}{n+3}\)
Gọi \(d\inƯC\left(2n+5;n+3\right)\Rightarrow3n+5⋮d;n+3⋮d\)
\(\Rightarrow2n+5⋮d\)và \(2\left(n+3\right)⋮d\)
\(\Rightarrow\left[\left(2n+6\right)-\left(2n+5\right)\right]⋮d\)
\(\Rightarrow1⋮d\Rightarrow d=1\)
Vậy \(\frac{2n+5}{n+3}\)là phân số tối giản
\(B=\frac{2n+5}{n+3}=\frac{2\left(n+3\right)+5-6}{n+3}=\frac{2\left(n+3\right)-1}{n+3}=2-\frac{1}{n+3}\)
Với \(B\in Z\)để n là số nguyên
\(\Rightarrow1⋮n+3\Rightarrow n+3\inƯ\left(1\right)=\left\{\pm1\right\}\)
\(\Rightarrow n\in\left\{-2;-4\right\}\)
Vậy.....................
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a, \(\frac{2n+5}{n+3}\)Đặt \(2n+5;n+3=d\left(d\inℕ^∗\right)\)
\(2n+5⋮d\) ; \(n+3⋮d\Rightarrow2n+6\)
Suy ra : \(2n+5-2n-6⋮d\Rightarrow-1⋮d\Rightarrow d=1\)
Vậy tta có đpcm
b, \(B=\frac{2n+5}{n+3}=\frac{2\left(n+3\right)-1}{n+3}=\frac{-1}{n+3}=\frac{1}{-n-3}\)
hay \(-n-3\inƯ\left\{1\right\}=\left\{\pm1\right\}\)
| -n - 3 | 1 | -1 |
| n | -4 | -2 |
cho phan so \(B=\frac{4n+1}{2n-3}\)n thuoc z
a, tim n de phan so B toi gian
b, tim n de B dat gia tri nho nhat , gia tri lon nhat va tinh cac gia tri do.
tim cac so tu nhien n de cac phan so sau la phan so toi gian a) 2n+3:4n+1 b) 3n+2:7n+1 c) 2n+7:5n+2
Cho cac bieu thuc
A=n+6 phan n-5 va B=3n-9 phan n-6
a/ Tim gia tri nguyen cua n de A, B la phan so ?
b/ Tim gia tri nguyen cua n de A, B co gia tri nguyen?
c/ Tim gia tri nguyen cua n de A, B co gia tri nguyen lon nhat?
Cho: A= \(\frac{n+1}{n-3}\)
a) Tim nde A la phan so.
b) Tim n de A la phan so toi gian.
c) Tim n de A co gia tri lon nhat.