mohon dijawab pakai jalan ya

Bab Persamaan Garis dan Bangun Datar
Matematika SMP Kelas VIII

19] 2x + 5y = 11 → dikali 3 menjadi 6x + 15y = 33
      3x - 2y = -12 → dikali 2 menjadi 6x - 4y  = -24
                                                         ------------------- -
                                                                   19y = 57
                                                                       y = 3
2x + 5y = 11
2x + 5 . 3 = 11
2x = 11 - 15
x = -4/2
x = -2

2x + 2y = 2 . (-2) + 2 . 3 = -4 + 6 = 2

jawabannya A

QR = √(30² - (32 - 14)²)
QR = √(900 - 324)
QR = √576
QR = 24 cm

jawabannya C

Mapel : Matematika
Kelas : VIII SMP
Bab : SPLDV

Pembahasan :
19||

2x + 5y = 11 ——» x = (11 - 5y)/2
3x - 2y = -12

Substitusi...
3x - 2y = -12
3(11 - 5y)/2 - 2y = -12
(33 - 15y)/2 - 2y = -12
33 - 15y - 4y = -24
33 + 24 = 19y
19y = 57
y = 3

Substitusi...
x = (11 - 5y)/2
x = (11 - 5.3))/2
x = (11 - 15)/2
x = -4/2
x = -2

Maka...
2x + 2y
= 2(-2) + 2(3)
= -4 + 6
= 2

20||

Pakai Teorema Pythagoras
QR² = PS² - (32 - 14)²
QR² = 30² - 18²
QR² = 900 - 324
QR² = 576
QR = √576
QR = 24 cm