diketahui kesamaan 5x^2 - 2x + 3 = kx^2 + (m + n) x + 7 (m- n). nilai K + 8m - 6n =

saya coba dulu ya kk
[tex] {5x}^{2} - 2x + 3 \\ {kx}^{2} + (m + n)x + 7(m - n) \\ maka \\ k = 5 \\ m + n = - 2 \\ 7(m - n) = 3[/tex]
cari dulu nilai m dan n

eliminasi m
[tex]m + n = - 2 \: \: \: \: \: \: \: \: \: \: \: \: \: \: \times 7\\ 7m - 7n = 3 \: \: \: \: \: \: \: \: \: \: \times 1 \\ [/tex]
7m + 7n = -14
7m - 7n = 3
__________-
14n = - 17
n = - 17/14

[tex]n = \frac{ - 17}{14} \: \: subtitusi \: ke \\ 7m - 7n = 3 \\ 7m - 7. \frac{ - 17}{14} = 3 \\ 7m + \frac{17}{2} = 3 \\ 7m = 3 - \frac{17}{2} \\ 7m = \frac{6 - 17}{2} \\ 7m = \frac{ - 11}{2} \\ m = \frac{ - 11}{2} \times \frac{1}{7} \\ m = \frac{ - 11}{14} [/tex]
jadi
[tex]k + 8m - 6n \\ = 5 +8 . \frac{ - 11}{14} -6. \frac{ - 17}{14} \\ = \frac{70}{14} - \frac{88}{14} + \frac{102}{14} \\ = \frac{84}{14} = 6[/tex]




Alhamdulillah kk..
semoga terbantu
maaf kalo salah