suatu persegi panjang,panjangnya (2x+7)cm dan lebarnya (3x-2)cm.Jika kelilingnya 50cm maka luasnya? a)150cm b)130cm c)120cm d)100cm

PERSEGI PANJANG

K = 50
2×(p + l) = 50
p + l = 50/2
p + l = 25
2x + 7 + 3x - 2 = 25
2x + 3x = 25 - 7 + 2
5x = 20
x = 20/5
x = 4 cm

p = 2x + 7 = 2×4 + 7 = 8+7 = 15 cm
l = 3x - 2= 3×4 -2 = 12-2 = 10 cm

Luas = 15 × 10 = 150 cm^2

Bab Bangun Datar
Matematika SMP Kelas VII

persegi panjang
keliling = 2 . (p + l) = 50
2x + 7 + 3x - 2 = 50 : 2
5x = 25 - 5
x = 20 : 5
x = 4

p = 2x + 7
p = 2 . 4 + 7
p = 15 cm

l = 3x - 2
l = 3 . 4 - 2
l = 10 cm

luas = p x l
luas = 15 x 10
luas = 150 cm²

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