b) 2.27<- 3^n<- 243
c) 16< 2^n < 2^2n-3 * 2^8-2n
a) 58.75+2.50.9-25.29 b) 3.9.39+3.9.63-2.27 mong mọi người giúp mình
a) \(58.75+2.50.9-25.29=25.58.3+2.2.25.9-25.29=25\left(58.3+4.9-29\right)=25.181=4525\)b) \(3.9.39+3.9.63-2.27=27.39+27.63-27.2=27\left(39+63-2\right)=27.100=2700\)Chúc cậu học tốt!
tính nhanh các phép tinh:
A=8.17.125
b=4.37.25
c= 58.75+58.50-5825
d=27.39+27.63-2.27
\(A=8\cdot17\cdot125=\left(125\cdot8\right)\cdot17=1000\cdot17=17000\)
\(B=\left(25\cdot4\right)\cdot37=100\cdot37=3700\)
\(C=\left(75+50-25\right)\cdot58=100\cdot58=5800\)
\(D=\left(39+63-2\right)\cdot27=100\cdot27=2700\)
A=8.17.125= (8.125).17= 1000.17=17000
b=4.37.25=(4.25).37=100.37=3700
c= 58.75+58.50-58.25= 58.(75+50 - 25)= 58.100=5800
d=27.39+27.63-2.27= 27.(39+63-2)=27.100=2700
27.39+27.63-2.27
\(27\cdot39+27\cdot63-2\cdot27\)
\(=27\cdot\left(39+63-2\right)\)
\(=27\cdot100\)
\(=2700\)
27.39+27.63-2.27
=27.(39+63-2)
=27.100
=2700
27.39 + 27.63 - 2.27 =
27 . 39 + 27. 63 - 2 . 27
= 27 . (39 + 63 - 2 )
=27 . 100 = 2700
27.39 + 27.63 -2.27
= 27 . [ 39 + 63 - 2 ]
= 27 . 100
= 2700
Click mình mình click lại 3 cái !
27.39 + 27 . 63 - 2 . 27
= 27 x ( 39 + 63 - 2 )
= 27 x 100
= 2700
tính nhanh 27.39+27.63-2.27
1.04680504681 k cho mình
8^x + 18^x = 2.27^x
ta có
với x=0 pt trở thành \(8^0+18^0=2.27^0\Rightarrow1+1=2\left(ld\right)\)
\(f\left(x\right)=8^x+18^x\)
ta tính \(f'\left(x\right)=ln8.8^x+ln18.18^x>0\)
hàm số f(x) luôn đồng biến
mặt khác \(y=2.27^x\)có \(y'=2.ln27.27^x>0\) hàm số y luôn đồng biến
suy ra nghiệm của pt x=0
Logarit
3.8^x+4.12^x-18^x-2.27^x=0
Chia 2 vế cho \(27^x\) ta được:
\(3\left(\dfrac{8}{27}\right)^x+4\left(\dfrac{12}{27}\right)^x-\left(\dfrac{18}{27}\right)^x-2=0\)
\(\Leftrightarrow3\left(\dfrac{2}{3}\right)^{3x}+4\left(\dfrac{2}{3}\right)^{2x}-\left(\dfrac{2}{3}\right)^x-2=0\)
Đặt \(\left(\dfrac{2}{3}\right)^x=t>0\)
\(\Rightarrow3t^3+4t^2-t-2=0\)
\(\Leftrightarrow\left(t+1\right)^2\left(3t-2\right)=0\)
\(\Rightarrow t=\dfrac{2}{3}\Rightarrow\left(\dfrac{2}{3}\right)^x=\dfrac{2}{3}\)
\(\Rightarrow x=1\)
1)Tính nhanh
98.27+2.27
( 98 + 2 ) nhân 27
= 100 nhân 27
= 2700
2.27/40x-3/4/15=2/12
TÍNH NHANH
a) 58.75+58.50-58.25
b)27.39+27.63-2.27
c)128.46+128.32+128.22
a)58.75+58.50-58.25
=58.(75+50-25)
=58.100
=5800
b)27.39+27.63-2.27
=27.(39+63-2)
=27.100
=2700
c)128.46+128.32+128.22
=128.(46+32+22)
=128.100
=12800
a) 58.75 + 58 . 50 - 58 . 25
= 58 . ( 75 + 50 - 25 )
= 58 . 100
= 5800
b) 27 . 39 + 27 . 63 - 2 . 27
= 27 . ( 39 + 63 - 2 )
= 27 . 100
= 2700
c) 128 . 46 + 128 . 32 + 128 . 22
= 128 . ( 46 + 32 + 22 )
= 128 . 100
= 12800
a) 58.75 + 58.50 - 58.25 = 58(75 + 50 - 25) = 58.100 = 5800
b) 27.39 + 27.63 - 2.27 = 27(39 + 63 -2) = 27.100 = 2700
c) 128.46 + 128.32 +128.22 = 128(46 + 32 + 22) = 128.100 = 12800