Respuesta :

Answer: k=±`12

Step-by-step explanation:

[tex]ax^2-bx+c=0\\\\9x^2-kx+4=0\\\\D=b^2-4ac\\\\a=9\ \ \ \ b=-k\ \ \ \ c=4\\\\D=0\\\\Hence,\\\\D=(-k)^ 2-4(9)(4)=0\\\\k^2-144=0\\\\k^2=144\\\\k^2=12^2[/tex]

Extract the square root of both parts of the equation:

[tex]k=б\sqrt{12^2} \\\\k=б12[/tex]

mhanifa

Answer:

  • k = - 12 or k = 12

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A perfect square trinomial is:

  • (a ± b)² = a² ± 2ab + b²

Given trinomial:

  • 9x² - kx + 4 = 0

Show this as:

  • (±3x)² - kx + (±2)² = 0

Compare and find possible values of k:

  • k = - 2(±3)(±2) = ± 12

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