Respuesta :
Answer:
[tex]k=14[/tex]
Step-by-step explanation:
Completing the square gives
[tex]x^4 + kx^2 + 49\\= (x^2+7)^2 - 14x^2 + kx^2[/tex]
So we have to cancel the latter two terms out for the expression to always become a square (otherwise we are dealing with a square plus something else, which doesn't always result in a square), giving us our answer directly.
Answer:
k=± 14
Step-by-step explanation:
[tex]x^4+kx^2+49\\Disc.=b^2-4ac=k^2-4*1*49\\it ~ is ~a ~ perfect ~ square.\\k^2-196=0\\k^2=196\\k= \pm 14[/tex]
