x : 1/5 =125
Tính nhanh
( 1+3+5+7+…+2003+2005) x (125 125 x 127 – 127 127 x 125)
( 1+3+5+7+…+2003+2005) x (125 125 x 127 – 127 127 x 125)
= ( 1+3+5+7+…+2003+2005) x (125 x 1001 x 127 – 127 x 1001x 125)
= ( 1+3+5+7+…+2003+2005) x 0 = 0
1.tính bằng 2 cách
a,(125 x 63) :5 = (125 x 63 ) : 5 =
= =
Cách 1: a. (125.63):5=7875:5
=1575
Cách 2: a. (125.63):5=(125:5).63
=25.63
=1575
(Bạn sửa dấu " . " thành dấu nhân giúp mik nhé)
Cách 1: a. (125.63):5=7875:5
=1575
Cách 2: a. (125.63):5=(125:5).63
=25.63
=1575
(Bạn sửa dấu " . " thành dấu nhân giúp mik nhé)
Tính nhanh:
a. ( 1+3+5+7+…+2003+2005) x (125 125 x 127 – 127 127 x 125)
b. 19 , 8 : 0 , 2 x 44 , 44 x 2 x 13 , 2 : 0 , 25 3 , 3 x 88 , 88 : 0 , 5 x 6 , 6 : 0 , 125 x 5
a. Vì 125 125x127 – 127 127x125 = 1001x125x127 – 1001x127x125 = 0
nên : (1+3+5+...+2005)(125 125x127 – 127 127x125) = 0
b.
19 , 8 : 0 , 2 x 44 , 44 x 2 x 13 , 2 : 0 , 25 3 , 3 x 88 , 88 : 0 , 5 x 6 , 6 : 0 , 125 x 5 = 19 , 8 x 5 x 88 , 88 x 13 , 2 x 4 3 , 3 x 88 , 88 x 2 x 6 , 6 x 8 x 5 = 19 , 8 x 5 x 88 , 88 x 13 , 2 x 4 3 , 3 x 88 , 88 x 13 , 2 x 4 x 2 x 5 = 19 , 8 3 , 3 x 2 = 3
Tính nhanh:
( 1 + 3 + 5 + 7 + … + 2003 + 2005 ) x ( 125 125 x 127 )
Vì 125 125x127 – 127 127x125 = 1001x125x127 – 1001x127x125 = 0
nên : (1+3+5+...+2005)(125 125x127 – 127 127x125) = 0
26 x 5^x-1- 5^x-1=125
\(26\cdot5^{x-1}-5^{x-1}=125\)
\(\Rightarrow5^{^{x-1}}\cdot\left(26-1\right)=125\)
\(\Rightarrow5^{x-1}\cdot25=125\)
\(\Rightarrow5^{x-1}=\dfrac{125}{25}\)
\(\Rightarrow5^{x-1}=5\)
\(\Rightarrow x-1=1\)
\(\Rightarrow x=1+1\)
\(\Rightarrow x=2\)
\(\Leftrightarrow5^{x-1}\cdot\left(26-1\right)=125\)
=>\(5^{x-1}=5\)
=>x-1=1
=>x=2
Tính bằng cách thuận tiện:
(1+3+5+ ... + 145 +147 +149) x ( 125 125 x 127 – 125 x 127 127)
Tìm x : ( 5^2.x - 5^x+1) :5=125
26.5^x - 1 - 5^x - 1=125
a)42x - 6 = 1
b)2x-1= 16
c)5<5x<125
d)5x+1= 125
e)52x-3 - 2. 52 = 52 . 3
\(a,4^{2x-6}=1\)\(\Leftrightarrow2x-6=0\Leftrightarrow2x=6\Rightarrow x=3\)
\(b,2^{2x-1}=16\Rightarrow2^{2x-1}=2^4\)
\(\Rightarrow2x-1=4\Rightarrow2x=5\Rightarrow x=\frac{5}{2}\)
\(c,5< 5^x< 125\Rightarrow5^1< 5^x< 5^3\)\(\Rightarrow1< x< 3\)
\(d,5^{x+1}=125\Rightarrow5^{x+1}=5^3\Rightarrow x+1=3\Rightarrow x=2\)
\(a,4^{2x-6}=1\)
\(4^{2x-6}=4^0\)
\(\Rightarrow2x-6=0\)
\(\Rightarrow2x=6\Leftrightarrow x=3\)
\(b,2^{x-1}=16\)
\(2^{x-1}=2^4\)
\(\Rightarrow x-1=4\)
\(\Rightarrow x=5\)
a)4^2x-6=1=>4^2x-6=1=4^0 b)2^x-1=16=2^4 c) 5=5^1<5^x<125=5^3 d)5^x+1=125=5^3
=>2x-6=0=>2x=6=>x=3 =>x-1=4=>x=5 =>x=2 => x+1=3=>x=2
e)=>5^2x-3-50=75
=>5^2x-3=25=5^2
=>2x-3=2
=>2x=5=>x=5/2
x + 5678 = 9285 x : 1/5 = 125