(3x+4)mũ 3 +125=0
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Bài 9:
a) Ta có: \(A=\left(2x+y\right)^2-\left(2x+y\right)\left(2x-y\right)+y\left(x-y\right)\)
\(=4x^2+4xy+y^2-4x^2+y^2-xy-y^2\)
\(=3xy-y^2\)
\(=3\cdot\left(-2\right)\cdot3-3^2=-18-9=-27\)
b) Ta có: \(B=\left(a-3b\right)^2-\left(a+3b\right)^2-\left(a-1\right)\left(b-2\right)\)
\(=a^2-6ab+9b^2-a^2-6ab-9b^2-ab+2a+b-2\)
\(=-13ab+2a+b-2\)
\(=-13\cdot\dfrac{1}{2}\cdot\left(-3\right)+2\cdot\dfrac{1}{2}+\left(-3\right)-2\)
\(=\dfrac{31}{2}\)
Bài 7:
a) \(498^2=\left(500-2\right)^2=250000-2000+4=248004\)
b) \(93\cdot107=100^2-7^2=10000-49=9951\)
c) \(163^2+74\cdot163+37^2=\left(163+37\right)^2=200^2=40000\)
d) \(1995^2-1994\cdot1996=1995^2-1995^2+1=1\)
e) \(9^8\cdot2^8-\left(18^4-1\right)\left(18^4+1\right)\)
\(=18^8-18^8+1=1\)
f) \(125^2-2\cdot125\cdot25+25^2=\left(125-25\right)^2=100^2=10000\)
\(\Leftrightarrow\left(3x-4\right)^3=5^3\\ \Leftrightarrow3x-4=5\\ \Leftrightarrow3x=9\\ \Leftrightarrow x=3\)
\(\left(3x-4\right)^3=125\)
\(\Leftrightarrow\left(3x-4\right)^3=5^3\)
\(\Rightarrow3x-4=5\Leftrightarrow3x=9\Leftrightarrow x=3\)
a) 4.25-12.5+170:10
=100-60+17
=40+17
=57
b) (7+33:32).4-3
=(7+3).4-3
=10.4-3
=40-3
=37
c) 12:{400:[500-(125+25.7)]}
=12:{400:[500-(125+175)]}
=12:{400:[500-300]}
=12:{400:200}
=12:2
=6
d) 168+{[2.(24+32)-2560]:72}
=168+{[2.(16+9)-1]:49}
=168+{[2.25-1]:49}
=168+{[50-1]:49}
=168+{49:49}
=168+1
=169
1.(x -5)^2 - 25 =0
=> (x - 5)^2 = 25
=> x - 5 = 5 hoặc x - 5 = -5
=> x = 10 hoặc x = 0
vậy_
2. (x -2)^3 =27
=> x - 2 = 3
=> x = 5
vậy_
3. 3(x -7) + 2x(x+2) = 2x^2
=> 3x - 21 + 2x^2 + 4x = 2x^2
=> 7x - 21 = 0
=> 7x = 21
=> x = 3
vậy_
4. (x^2 - 4) (x +8) =0
=> x^2 - 4 = 0 hoặc x + 8 = 0
=> x^2 = 4 hoặc x = -8
=> x = 2 hoặc x = -2 hoặc x = -8
vậy_
5. x^ 2 + 3x = 0
=> x(x + 3) = 0
=> x = 0 hoặc x + 3 = 0
=> x = 0 hoặc x = -3
vậy_
6. 3x^3 - 3x = 0
=> 3x(x^2 - 1) = 0
=> 3x(x - 1)(x + 1) = 0
=> x = 0 hoặc x = 1 hoặc x = -1
vậy_
7. (x +1)^2 = ( 2x +3)^2
=> (x + 1 + 2x + 3)(x + 1 - 2x - 3) = 0
=> (3x + 3)(-x - 2) = 0
=> x = -1 hoặc x = -2
vậy_
Bài làm
1) ( x - 5 )2 - 25 = 0
<=> ( x - 5 - 5 )( x - 5 + 5 ) = 0
<=> x( x - 10 ) =
<=> \(\orbr{\begin{cases}x=0\\x-10=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=10\end{cases}}}\)
Vậy S = { 0; 10 }
2) \(\left(x-2\right)^3=27\)
\(\Leftrightarrow\left(x-2\right)^3=3^3\)
\(\Leftrightarrow x-2=3\)
\(\Leftrightarrow x=5\)
Vậy x = 5 là nghiệm phương trình.
3) \(3\left(x-7\right)+2x\left(x+2\right)=2x^2\)
\(\Leftrightarrow3x+2x^2+4x-2x^2=21\)
\(\Leftrightarrow7x=21\)
\(\Leftrightarrow x=\frac{21}{7}=3\)
Vậy x = 3 là nghiệm phương trình
4) \(\left(x^2-4\right)\left(x+8\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x^2-4=0\\x+8=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x^2=\pm2\\x=-8\end{cases}}}\)
Vậy S = { 2; -2; -8 }
5) \(x^2+3x=0\)
\(\Leftrightarrow x\left(x+3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\x+3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=-3\end{cases}}}\)
Vậy S = { 0; -3 }
6) \(3x^3-3x=0\)
\(\Leftrightarrow3x\left(x^2-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}3x=0\\x^2-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=\pm1\end{cases}}}\)
Vậy S = { +1; 0 }
7) \(\left(x+1\right)^2=\left(2x+3\right)^2\)
\(\Leftrightarrow\left(x+1\right)^2-\left(2x+3\right)^2=0\)
\(\Leftrightarrow\left(x+1-2x-3\right)\left(x+1+2x+3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}-x-2=0\\3x+4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=-\frac{4}{3}\end{cases}}}\)
Vậy S = { -2; -4/3 }
# Học tốt #
a) 38 : 34 + 22 x 23 = 113
b) 3 x 42 - 2 . 3 = 42
c) 46 . 34 . 95 : 612 = 9
d) 212 . 14 . 125 : 353 . 6 = 108
e) 453 . 204 .182 : 1805 = 25
#BạcHà#
bn ơi ghi cả cách làm nữa bn
ai lm lun cách làm mk sẽ k cho 2 k lun
Bài 2:
a: \(\Leftrightarrow\left(x-5\right)\left(x+5\right)-\left(x+5\right)=0\)
=>(x+5)(x-6)=0
=>x=-5 hoặc x=6
b: \(\Leftrightarrow4x^2-4x+1-4x^2+1=0\)
=>-4x+2=0
hay x=1/2
c: \(\Leftrightarrow\left(x^2+4\right)\left(x^2-1\right)=0\)
=>x=1 hoặc x=-1
1/ a) \(2.3.12.12.3=2.3.2^2.3.2^2.3.3=2^5.3^4\)
b) \(3.5.27.125=3.5.3^3.5^3=3^4.5^4=\left(3.5\right)^4\)
2/ a) \(\left(27^3\right)^4=27^{3.4}=27^{12}\)
Vậy \(\left(27^3\right)^4=27^{12}\)
b) \(5^{36}=\left(5^6\right)^6\) và \(11^{24}=\left(11^4\right)^6\)
Do đó \(5^6=15625\) và \(11^4=14641\)
Vì 15625>14641 nên\(\left(5^6\right)^6>\left(11^4\right)^6hay5^{36}>11^{24}.\)
3/ a) \(x^3=125=>x=5\)
b) \(\left(3x-14\right)^3=2^5.5^2+200\)
\(\left(3x-14\right)^3=1000\)
\(3x-14=10^3\)
\(3x=10^3+14\)
\(3x=1014\)
\(x=\frac{1014}{3}=338\)
c) \(\left(2x-1\right)^4=81\)
\(\left(2x-1\right)^4=3^4\)
\(2x-1=3\)
\(2x=3+1\)
\(x=\frac{4}{2}=2\)
d) \(5x+3^4=2^2.7^2\)
\(5x+3^4=\left(2.7\right)^2=14^2\)
\(5x+81=196\)
\(5x=196-81\)
\(5x=115\)
\(x=\frac{115}{5}=23\)
e) \(4^x=1024=>x=5\).
`#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: \(243^{150}>216^{150}\Rightarrow3^{750}>6^{450}\)
....
\(\Rightarrow\left(3x+4\right)^3=-125=\left(-5\right)^3\\ \Rightarrow3x+4=-5\\ \Rightarrow3x=-9\\ \Rightarrow x=-3\)
(3x+4)\(^3\)+125=0
⇒(3x+4)\(^3\)=-125
⇒(3x+4)\(^3\)=-(5\(^3\))
⇒3x+4=-5
⇒3x=-9
⇒x=-3