QUKA
(QUIZ SUKA SUKA)
Tentukan titik balik atau nilai ekstrim dari grafik fungsi kuadrat
f(x)= 2x²-9x-18 , serta tentukan nilai dari f(3) !!
#drama?
(QUIZ SUKA SUKA)
Tentukan titik balik atau nilai ekstrim dari grafik fungsi kuadrat
f(x)= 2x²-9x-18 , serta tentukan nilai dari f(3) !!
#drama?
Verified answer
f(x) = 2x² - 9x - 18
a = 2
b = -9
c = -18
titik balik [tex] \displaystyle\tt~ \longmapsto (x_p, y_p ) [/tex]
[tex]\displaystyle\tt~x_p = - \frac{b}{2a} [/tex]
[tex]\displaystyle\tt~x_p = - \frac{b}{2a} = - \frac{( - 9)}{2(2)} = \frac{9}{4} = 2 \frac{1}{4} [/tex]
[tex]\displaystyle\tt~y_p = 2 {( \frac{9}{4} )}^{2} - 9( \frac{9}{4} ) - 18 \\ \\ \displaystyle\tt~ = \cancel{2}( \frac{81}{ {\cancel{16}}^{8} } ) - \frac{81}{4} - 18 \\ \\ \displaystyle\tt~ = \frac{81}{8} - \frac{162}{8} - \frac{144}{8} \\ \\ \displaystyle\tt~ = - \frac{ 225}{8} \\ \\ \displaystyle\tt~ = - 28 \frac{1}{8} [/tex]
koordinat titik balik [tex] \displaystyle\tt~ \longmapsto ( 2 \frac{1}{4} , - 28 \frac{1}{8} ) [/tex]
_________________
f(x) = 2x² - 9x - 18
f(3) = 2(3)² - 9(3) - 18
= 2(9) - 27 - 18
= 18 - 27 - 18
= -27