Persegi panjang dengan panjang 2(x+1) dan lebar (x-1) jika keliling persegi panjang 26 cmtentukan panjang dan lebar persegi panjang dan luas persegi panjang

p = 2(x+1) = 2x + 2
l = x - 1

keliling = 2p + 2l
26 = 2(2x + 2) + 2(x-1)
26 = 4x + 4 + 2x - 2
26 = 6x + 2
6x = 26 - 2
x = 24 / 6
x = 4

p = 2x + 2 = 2(4) + 2 = 8 + 2 = 10 cm
l = x - 1 = 4 - 1 = 3 cm

luas persegi panjang
= p x l
= 10 x 3
= 30 cm²

semoga membantu yaa..

Kelas 7 Matematika
Bab Persamaan Linear

Keliling = 26
2 . (p + l) = 26
2 (x + 1) + x - 1 = 26/2
2x + 2 + x - 1 = 13
3x = 13 - 1
x = 12/3
x = 4

p = 2 (x + 1)
p = 2 . (4 + 1)
p = 2 . 5
p = 10 cm

l = x - 1
l = 4 - 1
l = 3 cm

Luas = p . l
Luas = 10 . 3
Luas = 30 cm²