Question

Jika (a + 65)kuadrat = 15.625 maka (a +55)(a+75) =........

Mohon Bantuannya..

Answer 1

(a+65)^2 = 15625
(a+65) = akar dari 15625
a + 65 = 125
a = 125 - 65 = 30

(a+55)(a+75)
(30+55)(30+75)
(85)(105)
8925

Answer 2

Cara I
(a + 65)² = 15.625
(a + 65) = √15.625
(a + 65) = 125
a = 125 - 65
a = 60
(a + 55)(a + 75) ⇒ (60 + 55)(60 + 75) ⇒ 15.525

Cara II
misalkan a + 65 = x , maka :
a + 55 = (a + 65) - 10 = x - 10
a + 75 = (a + 65) + 10 = x + 10
(a + 55)(a + 75) = (x - 10)(x + 10)
(a + 55)(a + 75) = x² - 10²
(a + 55)(a + 75) = x² - 100
(a + 55)(a + 75) = 15.625 - 100
(a + 55)(a + 75) = 15.525


Cara II lebih keren bukan :)