If `f(x)=4x^4-a x^3+b x^2-c x+5 (a,b,c in R)` has four positive real zeros `r_1,r_2,r_3,r_4` such that `r_1/2+r_2/4+r_3/5+r_4/8=1.` then a is equal to

If f(x)=4x^(4)-ax^(3)+bx^(2)-cx+5(a,b,c in R) has four positive real zeros r_(1),r_(2),r_(3),r_(4) such that (r_(1))/(2)+(r_(2))/(4)+(r_(3))/(5)+(r_(4))/(8)=1. then a is equal to

Prove that 4 (r_1 r_2 + r_2 r_3 + r_3 r_1) = (a+b+c)^2

In triangle A B C , if r_1=2r_2=3r_3, then a : b is equal to 5/4 (b) 4/5 (c) 7/4 (d) 4/7

In triangle A B C , if r_1=2r_2=3r_3, then a : b is equal to 5/4 (b) 4/5 (c) 7/4 (d) 4/7

In triangle A B C , if r_1=2r_2=3r_2, then a : b is equal to 5/4 (b) 4/5 (c) 7/4 (d) 4/7

Let A= {(x,y) in R xx R |2x^(2)+2y^(2)-2x-2y=1}, B= {(x,y) in R xx R|4x^(2)+4y^(2)-16y+7=0} and C={(x,y) in R xx R |x^(2)+y^(2)-4x-2y+5 le r^(2)} . Then the minimum value of |r| such that A uu B sube C is equal to