3)ОДЗ x+6≥0⇒x≥-6⇒x∈[-6;∞)
3-/x+7/=x²+12x+36
3-x-7=x²+12x+36
x²+13x+40=0
x1+x2=-13 U x1*x2=40
x1=-8 не удов усл
x2=-5
4)ОДЗ x>-3 U x≥-1/4⇒x∈[-1/4;∞)
x+9=√(4x+1)(x+3)
x²+18x+81=4x²+12x+x+3
3x²-5x-78=0
D=25+936=961
x1=(5-31)/6=-13/6 не удов усл
x2=(5+31)/6=6
((a+1)(a-1)+1)^2/(a-1)^2:(a^4/(a-1)^2=(a^2-1+1)^2/(a-1)^2*(a-1)^2/a^4=a^4(a-1)^2/(a-1)^1*a^4=1
6,8 × 0,2 = 1,36.
4-6,8=-2,8
1,36/-2,8 = -136/280 = -34/70 = -17/35.
0,6х+1,2-1,2х+1,8=4х-20
23=4,6х
х=23/4,6=5