А) при х = -3 у равен -20 б) при у = 12 х равен 5
1
5^x=a
1/(a+31)-4/(5a-1)≤0
(5a-1-4a-124)/(a+31)(5a-1)≤0
(a-125)/(a+31)(5a-1)≤0
a=125 a=-31 a=1/5
_ + _ +
-------------(-31)----(1/5)---------[125]-----------
a<-31⇒5^x<-31 нет решения
1/5<a≤125⇒1/5<5^x≤125⇒-1<x≤3
x∈(-1;3]
2
1)4^x-29*26x+168≤0
2%x=a
a²-29a+168≤0
a1+a2=29 U a1*a2=168⇒a1=8 U a2=21
8≤a≤21⇒8≤2^x≤21⇒3≤x≤log(2)21
2)x²+(3x-25)/x(x-5)≥x²-1/(x-4)+5/x
(3x-25)+1/(x-4)-5/x≥0
(3x²-12x-25x+100+x²-5x-5x²+45x-100)/x(x-4)(x-5)≥0
(-x²+3x)/x(x-4)(x-5)≥0
x(x-3)/x(x-4)(x-5)≤0
(x-3)/(x-4)(x-5)≤0
x=3 x-4 x=5 x≠0
_ + _ +
---------[3]--------(4)----------(5)-----------
x∈(-∞;0) U (0;3] U (4;5)
Х-7-2х-9=-13
-х=16-13
х= -3
0,6+0,5у-1=у+0,5
-0,5у=0,5-0,6+1
0,5х=-0,9
х= - 1,8
А) 3а²-3b² = 3(a²-b²) = 3(a-b)(a+b)
б) 12m²-12n² = 12(m²-n²) = 12(m-n)(m+n)
в) ax²-ay² = a(x²-y²) = a(x-y)(x+y)
г) 2a²x-2b²x = 2x(a²-b²) = 2x(a-b)(a+b)