Question

find the value of k of 4 th question​

Answer 1

Answer:

4.k= 3 and 4

5.

Step-by-step explanation:

4.

${b}^{2} - 4ac = 0 \\ when \: the \: roots \: are \: equal \\ compare \: equation \: with \: a {x}^{2} + bx + c \\ a = 1 \: \: \: \: \: \: \: \: \: \: b = - 2k \: \: \: \: \: \: \: c = (7k - 12) \\ {b}^{2} - 4ac = 0 \\ ({ - 2k})^{2} - 4 \times 1 \times (7k - 12) = 0 \\ 4 {k}^{2} - 28k + 48 = 0 \\ 4( {k}^{2} - 7k + 12) = 0 \\ {k}^{2} - 7k + 12 \\ {k}^{2} - 3k - 4k + 12 = 0$

$k(k - 3) - 4(k - 3) = 0 \\ (k - 3)(k - 4) = 0 \\ k - 3 = 0 \: \: \: \: \: \: \: \: \: \: \: k - 4 = 0 \\ k = 3 \\ k = 4$