Question

Tolong dong plisssss .. tolong kasih penyelsaiann untuk soal pertemuan 3 no 1 -5 besok mau dikumpul

Answer 1

1. 3x² - 2x - 1= 0
a = 3, b = -2, c = -1
a > 0
D = b²-4ac --> D= (-2)²-4(3)(-1)
D = 16
D > 0
Jenis akar real berbeda

2.  ..?

3). x² - 2x + 5 = 0
x₁+x₂ = -b/a = 2
x₁ x₂ = c/a  = 5
x₁² + x₂² = (x₁+x₂)² - 2x₁.x₂ =(2²) - 2(5) = 4 - 10 = - 6

4. x² - 7x + 2 = 0
α+β = -b/a = -(-7)/1 = 7
α. β  = c/a = 2/1 = 2

α/β + β/α = (α² + β²)/αβ  = {(α+β)² - 2 αβ} /(α β) =
= (7²- 2(2)) / (2)
= (49-4)/2
= 45/2 

5. x² + 4x - 5 = 0
α+β = -4
α.β = -5

1/α² + 1/β² = (α²+β²)/(αβ)²= {(α+β)² -2αβ}/ (αβ)²
= (-4)²-2(-5) ] / [ -5)²
= 26/25