If sum of the square of zeros of the quadratic polynomial f(x)=x2-8x+k is 40 find the value of K

• K=12
  x^2-8x+k, If a,b are the roots of equation
  a+b=8 ---(i) & ab=k ---(ii)
  (a+b)^2=64=a^2+2ab+b^2, given a^2+b^2=40, so 2ab=24 or ab=k=12
• 11 years agoHelpfull: Yes(2) No(2)
• K=12 roots are ( 8+root(64-4k) )/2 and ( 8-root(64-4k) )/2 i.e R1,R2 Squaring and adding we get
  (R1)2 +(R2)2= (square(8)+square (root(64-4k)))/2 which is equal to 40 so
  64-2k=40 =>k=12
• 11 years agoHelpfull: Yes(1) No(1)