Tìm x :
10x - 6 = 64
Tìm x
a) 27x3 + 64 =0
b) -x2 -25 + 10x
a,\((3x)^3\)=-64(=)3x=-4(=)x=\(-\frac{4}{3}\)
ý b thiếu đề bài
a)\(27x^3+64=0\)
\(\Rightarrow27x^3=-64\)
\(\Rightarrow x^3=-\frac{64}{27}\)
\(\Rightarrow x^3=\left(-\frac{4}{3}\right)^3\)
\(\Rightarrow x=-\frac{4}{3}\)
Tìm x :
a, 1/4 x 2/6 x 3/8 x 4/10x....x30/62 x 31/64 = \(2^x\)
b, (x-1)3 = -27
c, (2x+1)2= 625
d, x2 + x = 0
tìm x
a) 8/5x+17 = 9/x-4
b) -35/6x+1 = 64/4-10x
c) -2/x-1 = 3/3-x
d) 5/8x+1 = 2/3-2x
1. Tìm 1 số tự nhiên x,biết
a.7*7x+1=343
b.23*2x=64
c.(3x-15)7=0
d.4(2x-6)=1
e.(3-x)10x:(3-x)20=1 (x khác 3)
f.(x-6)3=(x-6)2
a, 7.7x+1=343
7x+1+1=343
7x+2=343=73
=> x+2=3
x=3-2=1
b,23.2x=64
23+x=64=26
=> 3+x=6
x=6-3=3
c,(3x-15)7=0
=> (3x-15)=0
3x-15=0
3x=0+15
3x=15
x=15:3=5
d, 4(2x-6)=1
=> 4(2x-6)=40=1
=> 2x-6=0
2x=0+6=6
x=6:2=3
e, (3-x)10x:(3-x)20=1
Nx: Một số chia cho chính nó luôn bằng1
Có: 3-x=3-x
=> 10x=20
x=20:10=2
f, (x-6)3=(x-6)2
Ta có: Th1: 03=02=0
=> (x-6)3=(x-6)2=0
=> x-6 =0
x=0+6=6
Th2: 13=12=1
=> (x-6)3=(x-6)2=1
=> x-6=1
x=1+6=7
Sử dụng hằng đẳng thức , phân tích đa thức thành nhân tử
\(\frac{1}{64}x^6-125y^3\)
\(27a^3-54a^2b+36ab^2-8b^3\)
\(x^6-x^6\)
\(10x-25-x^2\)
\(a,\frac{1}{64}x^6-125y^3\)
\(=\left(\frac{1}{2}x\right)^6-\left(5y\right)^3\)
\(=\left(\frac{1}{4}x^2\right)^3-\left(5y\right)^3\)
\(\left(\frac{1}{4}x^2-5y\right)\left[\left(\frac{1}{4}x^2\right)^2+\left(\frac{1}{4}x^2\right).5y+25y^2\right]\)
\(b,27a^3-54a^2b+36ab^2-8b^3\)
\(=\left(3a\right)^3-3.2.\left(3a\right)^2b+3.3a.\left(2b\right)^2-\left(2b\right)^3\)
\(=\left(3a-2b\right)^3\)
\(c,x^6-x^6\)
\(=0\)
\(d,10x-25-x^2\)
\(=-x^2+10x-25\)
\(=-\left(x^2-10x+25\right)\)
\(=-\left(x-5\right)^2\)
Bài 1: Tìm x
a,(2x-3)2-10x2+15x=0
b,49.(x-5)2-4.(2x+1)=0
c,(x+6)2-8x-48=0
d,64.(2x+3)2-(x-6)2=0
a: \(\Leftrightarrow\left(2x-3\right)^2-5x\left(2x-3\right)=0\)
=>(2x-3)(-3x-3)=0
=>x=-1 hoặc x=3/2
b: \(\Leftrightarrow49\left(x^2-10x+25\right)-8x-4=0\)
=>\(49x^2-498x+1221=0\)
=>\(x\in\left\{6.03;4.13\right\}\)
c: \(\Leftrightarrow\left(x+6\right)\left(x+6-8\right)=0\)
=>(x-2)(x+6)=0
=>x=2 hoặc x=-6
d: =>\(\left(16x+24\right)^2-\left(x-6\right)^2=0\)
=>(16x+24+x-6)(16x+24-x+6)=0
=>(17x+18)(15x+30)=0
=>x=-2 hoặc x=-18/17
Tìm x, biết: 5 x 3 – 3 x 2 + 10 x – 6 = 0
b) Ta có: 5x3 – 3x2 + 10x – 6 = (5x3 + 10x )+ ( -3x2– 6)
= 5x(x2 + 2) – 3(x2 + 2) = (x2 + 2)(5x – 3)
Vậy (x2 + 2)(5x – 3) = 0 ⇒ 5x – 3 = 0 (vì x2 + 2 ≥ 0, với mọi x)
⇒x = 3/5
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)
tìm x : 2x(3x-5)=10x-6
=> 6x2 - 10x = 10x - 6
=> 6x2 - 20x + 6 = 0
=> 2(x - 3)(3x - 1) = 0
=> (x - 3)(3x - 1) = 0
=> x - 3 = 0 => x = 3
hoặc 3x - 1 = 0 => 3x = 1 => x = 1/3
Vậy x = 3 ; x = 1/3