Question

1. Diketahui fungsi f(×)=a× + b
Jika f(5)=27
F(-3)=-5
Maka nilai dari f(8)...

2. Diketahui f(×)=3-2×-×*2
Domain {×/-5_< × _<3,×€R}
Ditanya persamaan sumbu simetri parabola...

Answer 1

1.
f(x) = ax+b

f(5) = 27
a(5) +b = 27
5a + b = 27 ...........[1]

f(-3) = -5
a(-3) + b = -5
-3a + b = -5
b = 3a-5 .......[2]

substitusi [2] ke [1] didapat
5a+(3a-5) = 27
5a+3a-5 = 27
8a = 27+5
8a = 32
a = 32/8 = 4
subst a=4 ke [2]
b = 3(4)-5 = 12-5 = 7

f(x) = 4x+7
f(8) = 4(8) + 7
       = 32 +7 = 39


2. f(x) = 2-2x-x²
domain : {x|-5≤x≤3}

sumbu simetri = -b/2a
a=-1 b=-2 c=1
sumbu simetri = -b/2a = -(-2)/2(-1) = 2/-2 = -1