Question

Liat gambar ya. tolong bantu no 3&4 butuh bgt soalnya besok dikumpulin. makasih :)

Answer 1

3.    y= x-1,5  ....y= 1/2x²-x-4
      x-1,5 = 1/2x²-x-4 
      1/2x²-x - x - 4 + 1,5 =0
       1/2x²-2x  - 2,5 =0  (Kali 2) supaya mudah
        x² - 4x - 5 = 0
       ( x -5) (x + 1)=0
        jadi x1= 5...X2= -1
      y1= 5 - 1,5 = 3,5.....y2= -1 - 1,5 = -2,5
    jadi x1 + x2 + y1 + y2
            5 -  1   +  3,5 - 2,5 = 5...(b)
     

Answer 2

3. x - 3/2 = 1/2 x^2 - x -4
 0 = 1/2 x^2 -2x - 5/2
 0 = x^2 - 4x - 5
(x -5)(x+1) = 0
x = 5 atau x = -1
jika x = 5 maka y = 7/2
jika x = -1 maka y = -5/2
x1+x2 +y1+y2 = 5 -1 +7/2 -5/2 = 5 (jawab B)

4.x -2y +8 = 0
x = 2y - 8
4x^2 + 4xy + y^2 + 4x +2y +1 = 0
4(2y - 8)^2 + 4(2y-8)y + y^2 + 4(2y - 8) + 2y + 1 = 0
4 (4y^2 - 32y + 64) + 8y^2 - 32y + y^2 + 8y - 32+2y + 1 =0
16y^2 - 128y + 256 + 8y^2 - 32y + y^2 + 8y - 32 +2y +1 =0
25 y^2 - 150 y +225 = 0
y^2 - 6y + 9 = 0
(y-3)^2 = 0
y = 3 (Jawab D)