plz jawab tugas saya mtk

16.Diketahui:f(x)=2x+3
f(k)=9

Ditanya : nilai k=..?

Jawab : f(k)=9
f(9)=2x+3
=2(9)+3
=18+3
=21 (A)

18.Diketahui:2x+3y=8
3x+5y=14
x=a. y=b

Ditanya : 4a-3b

Jawab =2x+3y=8 | 3 | 6x+9y=24
3x+ 5y=14 | 2 | 6x+10y=28
------------------ -
-y =-4
y=4
Cari nilai x
2x+3y=8
2x+3(4)=8
2x+12=8
2x=8-12
2x=-4
x=-4/2
x=-2
X=a dan Y=b
4a-3b
=4(-2)-3(4)
=(-8)-12
=-20 (D)

↑ Semoga Membantu ↑

16) f(x) = 2x + 3
      f(k) = 2k + 3
        9  = 2k + 3
       2k = 9 - 3
         k = 6/2
         k = 3

17) y - y₁ = m (x - x₁)
      y - 9  = -3/4 (x - 8)
          y   = -3/4x + 6 + 9
          y   = -3/4x + 15
      y + 3/4x - 15 = 0 dikalikan 4
      4y + 3x - 60  = 0

18) x = a ; y = b
      2a + 3b = 8   dikalikan 3 -----> 6a + 9b   = 24
      3a + 5b = 14 dikalikan 2 -----> 6a + 10b = 28
                                                      ------------------- -
                                                             - b = - 4
                                                               b = 4
      2a + 3b   = 8
      2a + 3(4) = 8
                 2a = 8 -12
                   a = -4/2
                   a = - 2
jika 4a - 3b = 4(-2) - 3(4)
                   = -8 - 12
                   = -20