\(A=3-\dfrac{1}{4}+\dfrac{2}{3}-5-\dfrac{1}{3}+\dfrac{6}{5}-6+\dfrac{7}{4}-\dfrac{2}{3}\)
\(=-8+\dfrac{6}{4}-\dfrac{1}{3}+\dfrac{6}{5}\)
\(=-\dfrac{169}{30}\)
tính
a,[-5/8+(-3/4)]+15/6 b, 1/2-(3/4+-5/6)-7/12 c, 17/2-(-3/7+5/3) d,-3-2/3+[-10/9-25/3)-5/6
tính
a,[-5/8+(-3/4)]+15/6 b, 1/2-(3/4+-5/6)-7/12 c, 17/2-(-3/7+5/3) d,-3-2/3+[-10/9-25/3)-5/6
Tính hợp lí.
( 3 - 1/4 + 2/3 ) - ( 5 -1/3 - 6/5 ) - ( 6 - 7/4 + 3/2 )
5) (x– 5)(x – 1)= (x – 1)(x – 2)
6) 6(х - 3)(х — 4) - 6х(х — 2) = 4
7)-(x + 3)(x – 4) + (x + 1)(x – 1) = 10
8) (2x – 1)(x – 2) – (x + 3)(2x – 7) =3
9) (х - 5)(4 — х) — (х — 1)(х + 3) = -2x^2
10 (4x + 1)(x – 3) - (x- 7)(4x – 1)=15
11) (x + 1)(x² – x + 1) – x(x² – 3) = 4
12) (x – 3)(x² + 3x+9)+ x(5 – x²?) = 6x
13) (3x – 5)(x + 1)– (3x – 1)(x+ 1)=x - 4
14) 5(x – 3)(x – 7)– (5x+ 1)(x – 2)= 8
1. Tìm a,b,c biết:
a) a/b = 8/5; b/c = 2/7 và a+b+c= 61
b) ab = 1/2; bc= 2/3; ac = 3/4
c) 3a=2b; 5b = 7c và 3a + 5c - 7b= 60
2. tìm các số nguyên n sao cho:
1) 5^n + 5^n+2 = 650
2) 32^-n .16^n = 1024
3) 3^-1 .3^n+ 5. 3^n-1 = 162
4) 125. 5\(\ge\)5^n\(\ge\)5 . 25
5) (n^54)^2 = n
6) 243\(\ge\)3^n\(\ge\)9.27
7) 2^n+3 . 2^n = 144
8)3<3^n\(\le\)234
9) 8. 16\(\ge\)2^n\(\ge\)4
10) 4^15. 9^15<2^n.3^n< 18^16. 2^16
11) 4^11. 25^11\(\le\)2^n. 5^n\(\le\)20^12. 5^12
12)\(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}\).\(\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}\)= 2^n
13) 9. 27^n= 3^5
14) (2^3 : 4) . 2^n= 4
15) 3^-2 . 3^4. 3^n = 3^7
16)2^-1. 2^n +4.2^n=9.2^5
Tính
a) \(\dfrac{-2}{3}+\dfrac{3}{4}-\dfrac{-1}{6}+\dfrac{-2}{5}\)
b) \(\dfrac{-2}{3}+\dfrac{-1}{5}+\dfrac{3}{4}-\dfrac{5}{6}-\dfrac{-7}{10}\)
1. So sánh:
a) 25^50 và 2^300
b) 625^15 và 12^45
2. Tính hợp
a) -4 5/7 . 33 1/3 + 4 5/7 . 47 . 1/3
b) (3/5 + 5 2/3 ) : 121/19 + ( -5 2/3 + 2/3 ) : 121/19
c)( -1/4) . ( 6 2/11) + 3 9/11 . (-1/4)
d) 4 . ( -1/3)^3 - 2 . ( -1/2)^2 + 3. (-1/2) +1
3. Tìm x
a) GTTĐ của x - 2 = 5
b) 3x . ( x - 2/5) = 0
c) 3 ^x+2 +3^x = 270
d) 3/4 + 1/4 :x = 2/5
e) (9/5 - x)^2 = 16/25
Tính :
A = \(\dfrac{\dfrac{3}{7}-\dfrac{3}{11}+\dfrac{3}{13}}{\dfrac{5}{7}-\dfrac{5}{11}+\dfrac{5}{13}}+\dfrac{\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{4}}{\dfrac{5}{4}-\dfrac{5}{6}+\dfrac{5}{3}}\)
c) 7/23 x [(-8/6) - 45/18]
d) 23 1/4: 7/5 - 13 1/4 : 5/7
e) 25 x 153 / 63 x 102
l) (1/3)10 x (9)25 - (2/3)10 : (4/9)5
i) (-5)7 x (-1/5)7 + 0.56 x (-2)6
