5^log8 27/3^log2 5= 5^(log 2^3 3^3)/3^log2 5 = 5^(log2 3)/3^log2 5 = 3^(log2 5)/3^(log2 5)=1
b^loga c=c^loga b
решение задания смотри на фотографии
3^x • 3^y = 81
3^x + 3^y = 18
•••••••
3^x = a ; 3^y = b
ab = 81
a + b = 18
a = 18 - b
b( 18 - b ) = 81
18b - b^2 = 81
b^2 - 18b + 81 = 0
D = 324 - 324 = 0
b = 18 : 2 = 9
a = 18 - 9 = 9
••••••••
3^x = a
3^x = 9
3^x = 3^2
X = 2
3^y = b
3^y = 9
y = 2
Ответ ( 2 ; 2 )
<span>180*40=7200</span>
<span>230*70= 16100</span>
<span>430+120=550</span>
<span>270-40=230</span>
<span>500-30=470</span>
<span>25:20= 1.25</span>
<span>Вот так!</span>