7) 1,25^(3x-15) ≤1,25^0; 3x-15≤0; x≤15/3; x≤5 3)
8) {2x+1>0; {x>-0,5
{1-x>0; {x<1 //////////////////////////////////////////<br> {2x+1≤1-x; {x≤0 -------------(-0,5)----------0-------1------------>x
////////////////////////// x⊂(-0,5;0) 2)
9) x=1; x=4; x≠-5
+ - + -
--------------(-5)-------1-----------4------------->x
//////////////////// ////////////// x⊂(-∞;-5) ∪[1;4] 1)
10(1/2)^(x+2)≥4
2^(-x-2)≥2^2; -x-2≥2; -x≥4; x≤-4 3)
11) не вижу основание!
12) ((x-6+2*(-7-x))/(-7-x)≤0 + - +
( (x-6-14-2x)/(x+7))≥0;
-----------------(-20)-----------(-7)----->x
/////////////////////
(-x-20)/(x+7)≥0; (x+20)/(x+7)≤0; x⊂[-20; -7) 4)
13) 2^(x-4)≥2; x-4≥1; x≥5 x⊂[5;+∞)