Diketahui: 4x + 7y=15 dan 7x + 4y=18. Nilai xpangkat2 +ypangkat2 adalah sama cara lengkapnya ya

Mapel : Matematika
Kelas : VIII SMP
Bab : SPLDV

Pembahasan :
16x + 28y = 60
49x + 28y = 126
————————— (-)
33x = 66
x = 2

4x + 7y = 15
4(2) + 7y = 15
8 + 7y = 15
7y = 7
y = 1

Nilai x² + y² = 2² + 1² = 5

Eliminasi x:
4x + 7y = 15 || ×7
7x + 4y = 18 || ×4
⬇
28x + 49y = 105
28x + 16y = 72
_____________—
33y = 33
y = 33/33
y = 1

Substitusi y = 1 ke pers. 4x + 7y = 15
4x + 7y = 15
4x + 7(1) = 15
4x + 7 = 15
4x = 15 - 7
4x = 8
x = 8/4
x = 2

Maka:
x² + y²
= 2² + 1²
= 4 + 1
= 5 ✔