0,4·√10·√250+√169=0,4·√10·√25·√10+√169=0,4·5·10+13=33
6^(2log₆ 5) = 6^(log₆ 5²)= 5² = 25
если (6^(2log₆ 5))² = (6^(log₆ 5²))²= (5²)² = 25² = 625
log(a) b^k = k* log(a) b
a^(log(a) b)= b
Cosacos2a-cos3acos4a=sin2asin5a
(cos3a+cosa)/2 - (cos7a+cosa)/2 = (cos3a-cos7a)/2
(cos3a+cosa-cos7a-cosa)/2=(cos3a-cos7a)/2
(cos3a-cos7a)/2=(cos3a-cos7a)/2
ч.т.д.
14y-9x=5 12x+21y=3
4х+7у=0
7у=-4х
-8х-9х=5
-17х=5
х=-5/17
<span>у=73/119</span>