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a. x mũ 2 - 2x + 1 = 25
= x^2 + 2.x.1 + 1^2
= ( x + 1 ) ^2
ko bt có đúng ko nữa, mấy câu kia tui ko bt lm
1. \(x^6-2x^3+1=0\Leftrightarrow\left(x^3-1\right)^2=0\Leftrightarrow x=1\)
2. \(x^6+\dfrac{1}{4}x^3+\dfrac{1}{64}=0\Leftrightarrow\left(x^3\right)^2+2.x^3.\dfrac{1}{8}+\left(\dfrac{1}{8}\right)^2=0\Leftrightarrow\left(x+\dfrac{1}{8}\right)^2=0\Leftrightarrow x=-\dfrac{1}{2}\)4. \(x^3-10x^2+25x=0\Leftrightarrow x^3-5x^2-5x^2+25x=0\)
\(\Leftrightarrow x^2\left(x-5\right)-5x\left(x-5\right)=0\)
\(\Leftrightarrow x\left(x-5\right)^2=0\Leftrightarrow x=5\)
5. \(\dfrac{1}{4}x^3-3x^2+9x=0\)
\(\Leftrightarrow x\left(\dfrac{1}{4}x^2-3x+9\right)=0\)
\(\Leftrightarrow x\left[\left(\dfrac{1}{2}x\right)^2-2.\dfrac{1}{2}x.3+3^2\right]=0\)
\(\Leftrightarrow x\left(\dfrac{1}{2}x-3\right)^2=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=6\end{matrix}\right.\)
6. \(x^5-16x=0\Leftrightarrow x\left(x^4-16\right)=0\Leftrightarrow x\left(x^2-4\right)\left(x^2+4\right)=0\)
\(\Leftrightarrow x\left(x-2\right)\left(x+2\right)\left(x^2+4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\\x^2=-4\left(l\right)\end{matrix}\right.\)
7. \(4x^2+4x-3=0\Leftrightarrow4x^2-2x^2-6x-3=0\)
\(\Leftrightarrow2x\left(2x-1\right)-3\left(2x-1\right)=0\)
\(\Leftrightarrow\left(2x-1\right)\left(2x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{3}{2}\end{matrix}\right.\)
8. \(4x^2+28x+48=0\Leftrightarrow4x^2+12x+14x+48=0\)
\(\Leftrightarrow4x\left(x+3\right)+12\left(x+4\right)=0\)
\(\Leftrightarrow\left(4x+12\right)\left(x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-4\end{matrix}\right.\)
9. \(9x^2-12x+3=0\Leftrightarrow9x^2-9x-3x+3=0\Leftrightarrow9x\left(x-1\right)-3\left(x-1\right)=0\Leftrightarrow\left(x-1\right)\left(9x-3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{1}{3}\end{matrix}\right.\)
Bài 1:
29.(85-47)+85.(47-29)
=29.38+85.18
=1102+1530
=2632
BÀI 2
a, 15x = -75
x =( -75) : 15
x = -5
Vậy x= -5
b,-5x+8=-27
-5x = -27 - 8
-5x= -35
x =-35 : -5
x = 7
Vậy x = 7
c,3.(17 + x ) = - 42
17 + x = - 42 : 3
17 + x = -14
x = - 14 - 17
x = -31
Vậy x = - 31
d,-10 -( 2x -16) = 0
2x - 16 = 10-0
2x - 16 = 10
2x = 10 +16
2x = 26
x = 26 : 2
x = 13
Vậy x = 13
e,( mik ko bít làm)
f,( tự làm nghen bạn)
a, 273 : 35 = ( 33)3 : 35 = 39 : 35 = 34
b, 72 . 343 . 4930 = 72. 73.(72)3 = 711
c, 625 : 53 = 54 : 53 = 5
d, 1 000 000 : 103 = 106 . 103 = 103
e, 115 : 121= 115 : 112 = 113
f, 87 : 64 :8 = 87 : 82 : 81 = 84
i, 1024 . 16 : 26 = 210 . 23 : 26 = 27
\(a,\left(-5\right).\left|x\right|=-75\)
\(\left|x\right|=\frac{-75}{-5}=15\)
\(\Rightarrow\orbr{\begin{cases}x=15\\x=-15\end{cases}}\)
Vậy....
\(b,\left(-6\right)^3.x^2=-1944\)
\(-216.x^2=-1944\)
\(x^2=9\)
\(\Rightarrow x=\pm3\)
Vậy....
\(d,\left|9-x\right|=-7+64\)
\(\left|9-x\right|=57\)
\(\Rightarrow\orbr{\begin{cases}9-x=57\\9-x=-57\end{cases}\Rightarrow\orbr{\begin{cases}x=-48\\x=66\end{cases}}}\)
Vậy...
\(e,\left|x+101\right|-\left(-16\right)=\left(-43\right).\left(-5\right)\)
\(\left|x+101\right|+16=215\)
\(\left|x+101\right|=199\)
\(\Rightarrow\orbr{\begin{cases}x+101=199\\x+101=-199\end{cases}\Rightarrow\orbr{\begin{cases}x=98\\x=-300\end{cases}}}\)
Vậy..
hok tốt!!
a,\(\left(-5\right).\left|x\right|=-75\)
\(=>\left|x\right|=-75:\left(-5\right)=15\)
\(=>\orbr{\begin{cases}x=15\\x=-15\end{cases}}\)
b,\(\left(-6\right)^3.x^2=-1944\)
\(=>\frac{1944}{216}=x^2\)
\(=>x=\sqrt{\frac{1944}{216}}=3\)
`#3107.101107`
a)
`64^150` và `4^450`
Ta có:
`64^150 = (4^3)^150 = 4^(3*150) = 4^450`
Vì `450 = 450 => 4^450 = 4^450 => 64^150 = 4^450`
Vậy, `64^150 = 4^450`
b)
`81^64` và `27^100`
Ta có:
`81^64 = (3^4)^64 = 3^(4*64) = 3^256`
`27^100 = (3^3)^100 = 3^(3*100) = 3^300`
Vì `256 < 300 => 3^256 < 3^300 => 81^64 < 27^100`
Vậy, `81^64 < 27^100`
c)
`125^1000` và `25^3000`
Ta có:
`125^1000 = (5^3)^1000 = 5^(3*1000) = 5^3000`
Vì `5 < 25 => 5^3000 < 25^3000 => 125^1000 < 25^3000`
Vậy, `125^1000 < 25^3000`
d)
`4^30` và `3^40`
Ta có:
`4^30 = 4^(3*10) = (4^3)^10 = 64^10`
`3^40 = 3^(4*10) = (3^4)^10 = 81^10`
Vì `64 < 81 => 64^10 < 81^10 => 4^30 < 3^40`
Vậy, `4^30 < 3^40`
m)
`2^5000` và `5^2000`
Ta có:
`2^5000 = 2^(5*1000) = (2^5)^1000 = 32^1000`
`5^2000 = 5^(2*1000) = (5^2)^1000 = 25^1000`
Vì `32 > 25 => 32^1000 > 25^1000 => 2^5000 > 5^2000`
Vậy, `2^5000 > 5^2000`
h)
`6^450` và `3^750`
Ta có:
`6^450 = 6^(150*3) = (6^3)^150 = 216^150`
`3^750 = 3^(150*5) = (3^5)^150 = 243^150`
Vì `216 < 243 => 216^150 < 243^150 => 6^450 < 3^750`
Vậy, `6^450 < 3^750`
0)
`333^444` và `444^333`
Ta có:
`333^444 = 333^(4*111) = (333^4)^111 = (3^4 *111^4)^111 = 81^111 * 111^444`
`444^333 = 444^(3*111) = (444^3)^111 = (4^3 * 111^3)^111 = 64^111 * 111^333`
Vì `81 > 64;` `111^444 > 111^333`
`=> 81^111 * 111^444 > 64^111 * 111^333`
Vậy, `333^444 > 444^333.`
a) Ta có:
\(64^{150}=\left(2^6\right)^{150}=2^{900}\)
\(4^{450}=\left(2^2\right)^{450}=2^{900}\)
Mà: \(2^{900}=2^{900}\Rightarrow64^{150}=4^{450}\)
b) Ta có:
\(81^{64}=\left(3^4\right)^{64}=3^{256}\)
\(27^{100}=\left(3^3\right)^{100}=3^{300}\)
Mà: \(3^{300}>3^{256}\Rightarrow27^{100}>81^{64}\)
c) Ta có:
\(125^{1000}=\left(5^3\right)^{1000}=5^{3000}\)
Mà: \(25^{3000}>5^{3000}\Rightarrow25^{3000}>125^{1000}\)
d) Ta có:
\(4^{30}=\left(4^3\right)^{10}=64^{10}\)
\(3^{40}=\left(3^4\right)^{10}=81^{10}\)
Mà: \(81^{10}>64^{10}\Rightarrow3^{40}>4^{30}\)
m) Ta có:
\(2^{5000}=\left(2^5\right)^{1000}=32^{1000}\)
\(5^{2000}=\left(5^2\right)^{1000}=25^{1000}\)
Mà: \(25^{1000}< 32^{1000}\Rightarrow2^{5000}>5^{2000}\)
h) Ta có:
\(6^{450}=\left(6^3\right)^{150}=216^{150}\)
\(3^{750}=\left(3^5\right)^{150}=243^{150}\)
Mà: \(243^{150}>216^{150}\Rightarrow3^{750}>6^{450}\)
....
a) \(\frac{3}{4}+\frac{2}{5}x=\frac{29}{60}\)
\(\frac{2}{5}x=\frac{29}{60}-\frac{3}{4}\)
\(\frac{2}{5}x=\frac{-4}{15}\)
\(x=\frac{-4}{15}:\frac{2}{5}\)
\(x=\frac{-2}{3}\)
b) \(x^4=16\)
\(x^4=2^4\)
\(x=2\)
c) \(\left(x+5\right)^3=-64\)
\(\left(x+5\right)^3=-4^3\)
\(x+5=-4\)
\(x=-4-5\)
\(x=-9\)
d) \(\left(x-\frac{3}{4}\right)^2=0\)
\(\left(x-\frac{3}{4}\right)^2=0^2\)
\(x-\frac{3}{4}=0\)
\(x=0+\frac{3}{4}\)
\(x=\frac{3}{4}\)
e) \(x:8,5=0,69:\left(-1,15\right)\)
\(x:8,5=-0,6\)
\(x=-0,6.8,5\)
\(x=-5,1\)
A.2/5x=29/60-3/4
2/5x=29/60-45/60
2/5x=-4/15
x=-4/15:2/5
x=4/15.5/2
x=-2/3
B. x mũ 4 = 42
-) x=2
C. (x+5) mũ 3 = -4 3
x+5 = -4
X= -4-5
X=-9
D. ( X -3/4)mũ 2=0 mũ 2
X= 0+3/4
X=3/4
E. X:8,5=-0,6
X=-0,6*8,5
X=5,1
\(4^{x-1}-64=0\)
\(\Leftrightarrow4^{x-1}=64\)
\(\Leftrightarrow4^{x-1}=4^3\)
\(\Rightarrow x-1=3\Leftrightarrow x=4\)
a)64:2mũ5×30×4
= 64 : 32 x 30 x 4
= 240
b)3 mũ 2× 5 - 2 mũ 2×7+2 mũ 0 × 5
= 9 x 5 - 4 x 7 + 1 x 5
= 45 - 28 + 5
= 22
c)2 mũ 3-5 mũ 3÷5 mũ 2 + 12×2 mũ 2
= 8 - 125 : 25 + 12 x 4
= 8 - 5 + 48
= 51
d)2[(7-3 mũ 3÷3 mũ 2) chia 2 mũ 2 + 99]-100
= 2[( 7 - 27 : 9) : 4 + 99] - 100
= 2[4 : 4 + 99] - 100
= 2. 100 - 100
= 200 - 100
= 100
e)4[(3 + 3^7:3^4)chia 10 + 97]-300
= 4[( 3 + 3^3) : 10 + 97] - 300
= 4[ 30 : 10 + 97 ] - 300
= 4. 100 - 300
= 400 - 300
= 100
f)2^2 x 5 [(5 mũ 2 cộng 2 mũ 3) chia 11 - 2] - 3^2 x 2
= 4 x 5 [ (25 + 8 ) : 11 - 2] - 9 x 2
= 20 [ 33 : 11 - 2] - 18
= 20. 1 - 18
= 20 - 18
= 2
x^3 - 64 = 0
x^3 = 0+64
x^3 = 64
Suy ra x^3 = 4^3 vì 64 = 4.4.4
Mà 4.4.4 = 4^3. Vậy x= 4
\(x^3-64=0\)
\(\left(x-4\right)\left(x^2+4x+16\right)=0\)
Dễ thấy \(x^2+4x+16=\left(x+2\right)^2+12>0\)
Nên x = 4