If `a+b+c=13` , `a^2+b^2+c^2=69` , then find `a b+b c+c a` . `-50` (b) 50 (c) 69 (d) 75

If a + b + c = 13, a^2 + b^2 + c^2 = 69, " then find " ab + bc + ca .

If a= 2b/3, b= 2c/3, and c=2d/3, then find the ratio of b and d:

"If A"= ({:(2, 3),(5, 1):}), B = ({:(a, b),(c, d):}) and AB = -13I, then find the value of a + b - c + d. (a) 5 (b) 3 (c) 2 (d) 1

If   ( a -5 )^2 + ( b - c )^2 + ( c - d )^2 + ( b + c + d - 9 )^2 = 0 , then find the value of ( a + b + c ) ( b + c + d ) is

If a : b = 2 : 3, b : c = 3 : 4, c : d = 4 : 5, find a : b : c : d.

If a^(2)+b^(2)+c^(2)-ab-bc-ca=0, then a+b=c( b) b+c=ac+a=b(d)a=b=c

If a= 89, b= -69, c= 8 then the value of 9(a+b)^(2) +49 c^(2) -42 (a+b)c is

If a!=b!=c\ a n d\ |{:(a, b, c), (a^2,b^2,c^2), (b+c, c+a, a+b):}|=0 then a+b+c=0 b. a b+b c+c a=0 c. a^2+b^2+c^2=a b+b c+c a d. a b c=0

If a : b=5:7 a n d c : d=2a :3b , t h e n a c : b d is 10 : 21 b. 20 : 38 c. 50 : 147 d. 50 : 151