Tìm x
4x3 + 12 = 120
3*2x - 3 = 45
1500 : [ ( 30x + 40) : x] =30
giup mình với ,có chi mik t lại cho
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
1500: [(30x + 40) : x]=30
=>(30x + 40): x = 1500 : 30
=>30x : x+ 40:x=50
=> 30 + 40 :x=50
=> 40 :x=50-30
=> 40:x=20
=>x=40:20
=>x=2
: [(30x + 40) : x] = 30(2x - 15)5 = (2x - 15)3
=>(30x+40):x=1500 : 30=50
40:x = 50-30
40:x=20
x=2
a) \(2x^2+5x-18\)
\(=2x^2-4x+9x-18\)
\(=2x\left(x-2\right)+9\left(x-2\right)\)
\(=\left(x-2\right)\left(2x+9\right)\)
b) \(4x^2-17x+15\)
\(=4x^2-12x-5x+15\)
\(=4x\left(x-3\right)-5\left(x-3\right)\)
\(=\left(x-3\right)\left(4x-5\right)\)
c) \(-8x^2+10x+7\)
\(=-8x^2-4x+14x+7\)
\(=-4x\left(2x+1\right)+7\left(2x+1\right)\)
\(=\left(2x+1\right)\left(-4x+7\right)\)
d) \(7x^2-30x+8\)
\(=7x^2-28x-2x+8\)
\(=7x\left(x-4\right)-2\left(x-4\right)\)
\(=\left(x-4\right)\left(7x-2\right)\)
e) \(-x^3+11x^2-30x\)
\(=x\left(-x^2+11x-30\right)\)
\(=x\left(-x^2+5x+6x-30\right)\)
\(=x\left[-x\left(x-5\right)+6\left(x-5\right)\right]\)
\(=x\left(x-5\right)\left(-x+6\right)\)
a) 2x\(^2\) + 5x - 18 = 2x\(^2\) + 9x - 4x - 18 = x(2x + 9) - 2(2x + 9) = (x-2)(2x-9)
b) 4x\(^2\) - 17x - 15 = 4x\(^2\) + 20x - 3x - 15 = 4x(x + 5 ) - 3(x + 5) = (4x - 3 )(x + 5)
c) -8x\(^2\) + 10x + 7 = -8x\(^2\) + 14x - 4x + 7 =-2x(4x - 7) - (4x - 7) = (-2x - 1)(4x - 7)
d) 7x\(^2\) - 30x + 8 = 7x\(^2\) + 2x + 28x + 8 = x(7x + 2) + 4(7x + 2) = (x + 4)(7x + 2)
e) - x\(^3\) + 11x\(^2\) - 30x = -x(x\(^2\) - 11x + 30) = -x(x\(^2\) - 5x - 6x + 30) = -x\(\left[x\left(x-5\right)-6\left(x-5\right)\right]\) = -x(x-6)(x-5)
Mình làm câu khó thôi nhé.
2x chia hết cho 3
=>(2x+x-x) chia hết cho 3
=>(3x-x) chia hết cho 3
3x chia hết cho 3=>x chia hết cho 3
=>x thuộc B(3)={0;3;6;...}
Vậy x thuộc {0;3;6;...ư}
a) x+3=12
x=12-3
x=9
b)(x-3):2=514:512
=>(x-3):2=52
=>(x-3):2=25
=>x-3=25.2
=>x-3=50
=>x=50+3
=>x=53
c)4x+3x=30-20:10
=>x(4+3)=30-2
=>7x=28
=>x=28:7
=>x=4
d)2x-138=23.32
=>2x-138=8.9
=>2x-138=72
=>2x=72+138
=>2x=210
=>x=210:2
=>x=105
a) x + 3 = 12
x = 12 - 3
x = 9
b) ( x - 3 ) : 2 = 514 : 512
( x - 3 ) : 2 = 514-12
( x - 3 ) : 2 = 52
( x - 3 ) : 2 = 25
x - 3 = 50
x = 53
c) 4x + 3x = 30 - 20 : 10
7x = 28
x = 4
d) 2x - 138 = 23 x 32
2x - 138 = 8 x 9
2x - 138 = 72
2x = 210
x = 105
a, \(4x^3+12=120\)
\(\Leftrightarrow4x^3=120-12\)
\(\Leftrightarrow4x^3=108\)
\(\Leftrightarrow x^3=108:4\)
\(\Leftrightarrow x^3=27\)
\(\Leftrightarrow x=3\)
b, \(3.2^x-3=45\)
\(\Leftrightarrow3.2^x=45+3\)
\(\Leftrightarrow3.2^x=48\)
\(\Leftrightarrow2^x=48:3\)
\(\Leftrightarrow2^x=16\)
\(\Leftrightarrow x=4\)
Câu c, bạn làm tương tự nha !
a, 4x^3 + 12 = 120 b,3.2^x-3=45 c, 1500:[(30x +40):x]=30
4x^3=120-12 3.2^x =45+3 (30x +40):x =1500:30
4x^3=108 3.2^x =48 (30x +40):x = 50
x^3=108:4 2^x =48:3 30x:x+40:x = 50
x^3=27 2^x =16 30+40:x=50
=> x^3= 3^3 2^x =2^4 40:x=50-30
=> x = 3 => x =4 40:x= 20
=>x=40:20
=>x=20 ( câu c tui có làm sai thì đừng trách nhé )
<=> 2x^2 +x-4x-2-5x-15=2x^2-6x+4+8x-2-2x
2x^2-8x-17-2x^2-2=0
-8x-19=0
x=-19/8
\(4x^3+12=120\)
\(\Rightarrow4x^3=108\)
\(\Rightarrow x^3=108:4=27=3^3\)
\(\Rightarrow x=3\)
\(3.2^x-3=45\)
\(\Rightarrow3.2^x=48\)
\(\Rightarrow2^x=16=2^4\Rightarrow x=4\)
\(1500:\left[\left(30x+40\right):x\right]=30\)
\(\Rightarrow\left(30x+40\right):x=50\)
\(\Rightarrow30x:x+40:x=50\)
\(\Rightarrow30+40:x=50\)
\(\Rightarrow40:x=20\Rightarrow x=2\)
thanks bn nhìu