Penjelasan dengan langkah-langkah:

a.

4x² = 12 - 13x

4x² + 13x - 12 = 0

(4x - 3)(x + 4) = 0

4x - 3 = 0

4x = 3

x = 3/4

x + 4 = 0

x = -4

jadi akar²nya x₁ = -4 atai x₂ = 3/4

b.

8x² = 18x - 9

8x² - 18x = - 9........bagi 8

x² - 18/8x = -9/8

(x - 18/16)² = -9/8 + (18/16)²

(x - 9/8)² = -9/8 + (9/8)²

(x - 9/8)² = -9/8 + 81/64

(x - 9/8)² = -72/64 + 81/64

(x - 9/8)² = 9/64

x - 9/8 = √(9/64)

x = 9/8 ± 3/8

x₁ = 9/8 + 3/8 = 12/8

x₁ = 3/2

x₂ = 9/8 - 3/8 = 6/8

x₂ =3/4

jadi akar²nya x₁ = 3/2 atau x₂ = 3/4

c.

5 + 3x = 4x²

4x² - 3x - 5 = 0

koefisien

a = 4 ; b = -3 ; c = -5

x₁,₂ = [-b ± √(b² - 4ac)]/2a

x₁,₂ = [-(-3) ± √((-3)² - 4(4)(-5)]/2(4)

x₁,₂ = [3 ± √(9 + 80)]/8

x₁,₂ = (3 ± √89)/8

x₁,₂ = 1/8 (3 ± √89)

x₁ = 1/8(3 + √89)

x₂ = 1/8(3 - √89)