Penjelasan dengan langkah-langkah:
luas lahan = 80 m³
panjang = 5x cm
lebar = (2x + 4) cm
Luas = panjang x lebar
80 = 5x (2x + 4)
80 = 10x² + 20x
10x² + 20x - 80 = 0
kedua ruas bagi dengan 10
x² + 2 - 8 = 0
(x + 4)(x - 2) = 0
x + 4 = 0
x = -4
atau
x - 2 = 0
x = 2
ambil nilai x yg positif x = 2
panjang
= 5x
= 5(2)
= 10 cm
pernyataan ( i ) salah
lebar
= (2x + 4)
= 2(2) + 4
= 8 cm
pernyataan ( ii ) salah
keliling = 2 x ( panjang + lebar )
K = 2 (10 + 8)
K = 2 × 18
K = 36 cm
pernyataan ( iii ) salah
panjang diaginal
d = √(p² + l²)
d = √(10² + 8²)
d = √(100 + 64)
d = √164
d = √4. √41
d = 2√41 cm
pernyataan ( iv ) benar
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Penjelasan dengan langkah-langkah:
luas lahan = 80 m³
panjang = 5x cm
lebar = (2x + 4) cm
Luas = panjang x lebar
80 = 5x (2x + 4)
80 = 10x² + 20x
10x² + 20x - 80 = 0
kedua ruas bagi dengan 10
x² + 2 - 8 = 0
(x + 4)(x - 2) = 0
x + 4 = 0
x = -4
atau
x - 2 = 0
x = 2
ambil nilai x yg positif x = 2
panjang
= 5x
= 5(2)
= 10 cm
pernyataan ( i ) salah
lebar
= (2x + 4)
= 2(2) + 4
= 8 cm
pernyataan ( ii ) salah
keliling = 2 x ( panjang + lebar )
K = 2 (10 + 8)
K = 2 × 18
K = 36 cm
pernyataan ( iii ) salah
panjang diaginal
d = √(p² + l²)
d = √(10² + 8²)
d = √(100 + 64)
d = √164
d = √4. √41
d = 2√41 cm
pernyataan ( iv ) benar