Question

URGENTLY REQUIRED... Please answer all these questions as my exam is tomorrow..I need to study.. please I WILL ALSO MARK YOU AS A BRAINLIST.. please

Answer 1

answer for 5th one -(a+b+c)^2=a^2+b^2+c^2+(ab+bc+ca)

substituting value given :

(15)^2=a^2+b^2+c^2+2(35)

225=a^2+b^2+c^2+70

225-70=a^2+b^2+c^2

Therefore a^2+b^2+c^2=155