1) x=18-6.4
x=11.6
2) 7x=11.9 / :7
x=1.7
3) 6x- 3x=2.2+0.8
3x=3.0
x=1
4) 5x-7x-7=9
-2x=9+7
-2x=16/ : (-2)
x= - 8
X^3+2x^2-4x-8=0
x^2(x+2)-4(x+2)=0
(x+2)(x^2-4)=0
x+2=0
x1=-2
x^2-4=0
(x+2)(x-2)=0
x+2=0 x-2=0
x2=-2 x3=2
Ответ: x1=-2; x2=2
X2+14x+48=x2+6x+8x+48
14x=6x+8x
14x=14x
X∈R
1)
(1/4)^(х-3) <= 2 <=>
[2^(-2)]^(х-3) <= 2 <=>
2^[-2(x-3)] <= 2^1 <=>
-2(x-3) <= 1 <=>
-2x +6 <= 1 <=>
-2x <= -5 <=>
x >= 2,5
Ответ: x∈[2,5;+∞)
2)
√(16+2х) =6 <=>
{16+2x >0
{16+2x =36
{2x >-16
{2x =36-16
{x >-8
{x =10
Ответ: x=10