Question

Rezolvati in R ecuatiile:
g) $-5 x^{2} + 20 = 0$
h) $3,7 x^{2} + 2,59 = 0$
i) $x^{2} +7x+12=0$
j) $6 x^{2} - 5x +1 = 0$
k)$x^{2} - 4x - 1 = 0$

Mulțumesc anticipat!

Answer 1

-5x²=-20⇔5x²=20⇒x²=20/5⇒x²=4⇒x=√4⇒x=2

37/10 ori x²=259/100
37x²×100=259×10
3700x²=2590
x²=2590/3700
x²=259/370
x²=7/10⇒x=√7/10⇒x=√7/√10⇒x=√70/10 *aici mai verifica la calcule)

Δ=b²-4ac⇒Δ=7²-4×1×12⇒Δ=49-48⇒Δ=1
x1=(-b+√Δ)/2a⇒x1=-7+1/2⇒x1=-6/2⇒x1=-3
x2=(-b-√Δ)/2a⇒x2=-7-1/2=-8/2=-4

Δ=b²-4ac=(-5)²-4×6×1=25-24=1
x1=(-b+√Δ)/2a=-(-5)+1/12=6/12=1/2
x2=(-b-√Δ)/2a=-(-5)-1/12=4/12=1/3

Δ=b²-4ac=(-4)²-4×1×(-1)=16-4×(-1)=16+4=20
x1=(-b+√Δ)/2a=-(-4)+√20/2=4+2√5/2
x2=(-b-√Δ)/2a=-(-4)-√20/2=4-2√5/2