Question

Tentukan m agar persamaan x^2-6mx-2x+14m+21=0 mempunyai 2 akar kembar,tlg dibantu

Answer 1

Akar kembar --- D = 0
b^2 - 4ac = 0
(-(6m+2)^2 - 4(1)(14m+21) = 0
36m^2 + 24m + 4 - 56m - 84 = 0
36m^2 - 32m - 80 = 0
9m^2 - 8m - 20 = 0
(9m+10)(m-2) = 0
m = -10/9 atau m = 2 

Answer 2

x² - 6mx - 2x + 14m + 21 = 0
x² - (6m + 2) x + 14m + 21 = 0
a = 1
b = - (6m + 2)
c = 14m + 21

syarat mempunyai akar kembar --> D = 0
b² - 4ac = 0
(- (6m + 2)² ) - 4.1.(14m + 21) = 0
36m² + 24m + 4 - 56m - 84 = 0
36m² - 32m - 80 = 0  --> kedua ruas dibagi 4
9m² - 8m - 20 = 0
(9m + 10) (m - 2) = 0
m = -10/9 atau m = 2


semoga membantu ya :)