Ta có :
\(3\le3^n:9< 27\)
=> \(3\le3^n:3^2< 27\)
=> \(3\le3^{n-2}< 27\)
=> \(3^{n-2}\) \(\in\left\{3;9\right\}\)
=> n - 2 \(\in\left\{1;2\right\}\)
=> n \(\in\left\{3;4\right\}\)
Vậy .......
tìm x biết
a ) x^2 - 2x+3 chia het cho x-1
b) 2x-3 + ( y-1)\(^2\) + ( 27-1 )\(^2\) \(\le\) 0
a) 273 : 32
b) (3/5)13 :(9/25)5
Tính:
\(\dfrac{3^6.45^4-15^3.\dfrac{1}{5^9}}{27^4.25^3+45^6}\)
tìm x
a) x.3/1/4+(-7/6).x-1/2/3=5/12
b)2/5+3/5.(3x-3,7)=-53/10
c)7/9:(2+3/4x)+5/9=23/27
BT3: Tìm x, biết:
7) \(\dfrac{-5}{17}+\dfrac{3}{17}\le\dfrac{x}{17}\le\dfrac{13}{17}+\dfrac{-11}{17}\)
8) \(\dfrac{2}{3}\left(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{1}{3}\right)\le\dfrac{x}{18}\le\dfrac{7}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)\)
tìm số x biết
a) \(\frac{7}{9}:\left(2+\frac{3}{4}x\right)+\frac{5}{9}=\frac{23}{27}\) b) \(\frac{-2}{3}.x+\frac{1}{5}=\frac{3}{10}\) c) \(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)
Giúp mik giải mấy đề toán này nha, gấp lắm:
1)Tìm x
2.3x = 10. 312 + 8. 274
2) So sánh
a) 523 và 6.52
b) 7. 213 và 216
c) 2115 và 275. 498
3)
a) Cho S = 1+2+22+23+.... + 29
So sánh S vs 5.28
b) Cho P = 1+3+32+33+.... + 320
So sánh P vs 321
1.2.3.4.5.6 + 27
Tổng trên có chia hết cho 3 , cho 9 ko?
Làm rõ ràng ra nhé!
a)x=\(\dfrac{1}{4}+\dfrac{2}{13}\)
b)\(\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}\)
c)\(\dfrac{-8}{3}+\dfrac{-1}{3}\le x\le\dfrac{-2}{7}+\dfrac{-5}{7}\)
d)\(\dfrac{-5}{6}+\dfrac{8}{3}\dfrac{29}{-x}\le x\le\dfrac{-1}{2}+2+\dfrac{5}{2}\)