Question

Чему равно (a^2+d^2)/(2ad) 
ЕСЛИ 
a/b = 8/3;
b/c = 3/4;
c/d = 5/2

Answer 1

a/b=8/3 ; b=3/8*a
b/c=3/4; c=4/3*b=4/3*3/8*a=a/2
c/d=5/2; d=2/5*c=2/5*a/2=a/5

$frac{ a^{2} + d^{2} }{2ad} = frac{ a^{2}+ (frac{a}{5}) ^{2} }{2a* frac{a}{5} } = frac{25 a^{2} + a^{2} }{25} : frac{2 a^{2} }{5} = frac{26 a^{2} }{25} * frac{5}{2 a^{2} } =$
$frac{13}{5} =6.5$