<span>5^x·3^y=135</span>
<span> 3^y-5^x+1=2</span>
<span>
</span>
<span>5^x·3^y=135</span>
<span> 3^y-5^x=2-1</span>
<span>
</span>
<span>5^x·3^y=135 Замена переменных 5^x=t , 3^y=u t*u=135</span>
<span> 3^y-5^x=1 u+t=1</span>
<span>
</span>
<span>t*u=135</span>
<span> u=1-t</span>
<span>подставляем в первое, имеем:</span>
<span>t(1-t)=135</span>
<span>t-t^2=135</span>
<span>t^2 -t +135=0</span>
<span>D=1-4*135 <0</span>
не имет решений
4.1*15\8-7\8*4.1=4,1
4.1*15=61,5
61,5\8=7,6875
7\8=0,875
0,875=3,5875
7,6875-3,5875=4,1
1)а(a-c+1)= a^2-ac+a
3)5x(x+y^2-5)=5x^2+10x-25x
5)-xy(3y^2+2x)= -3xy^2-2x^2y
7)2^2xy(4x-3y+5xy)= 16x^2y-12xy^2+20x^2y^2
13.2.
1)(x-a)(x+y)= x^2+ax-ax-ay= x^2-ay
3)(t+s)(b+k)=tb+tk+sb+sk
5)(a+2)(b-3)= ab-3a+2b-6
7)(d-4)(t+5)=dt+5d-4t-20
Х3-6х2+12х-4+х3+6х2+12х+4=2х(х2-1)+3
2х3+24х-2х3+2х=3
26х=3
х=3/26
4-5(6x-6)<span><54-40x
4-30x+30</span><span><54-40x
-30x+40x</span><span><54-30-4
10x</span><span><20
x</span><span><10
(-</span>∞;10)