20 & 21. Makasih. .....

Materi Persamaan Kuadrat

Perbaikan No21
x1,2 = (-8 +- akar 48)/8
= -1 +- 2 akar 3
x1 = -1 + 1/2 akar 3
x2 = -1 - 1/2 akar 3

Pilihannya kok asal :v

Persamaan Kuadrat


20)

3x² + 11x - 21 = 0

a = 3
b = 11
c = -21

D = b² - 4ac
= 11² - 4 . 3 . -21
= 121 + 252
= 373

x = ( -b ± √D) /2a

x = (- 11 + √373) / 6

x = (-11 - √373) /6


21)

4x² + 8x + 1 = 0

D = 8² - 4 . 1 . 4
D = 64 -16
D = 48

x = (-8 ± √48)/8
x = ( -8 ± 4√3) / 8
x = ( 4(-2 ± √3)) / 8
x = (-2 ±√3) / 2

x = (-1 + (1/2)√3)
x = (-1 - (1/2)√3)