Question

Resolva estas equações :
A) 4x² - 4x - 35 =0
B) 2x² - x - 1 = 0
C) 9x² - 18x - 7 = 0

Answer 1

A) Δ= $b^{2}$ - 4ac
Δ= 16+ 560
Δ= 576
x= -b +- raiz de delta/ 2a
x= 4 +- 24/ 8
x´= 28/8 = 7/2
x´´= -20/8= -5/2

Answer 2

para o delta "Δ" temos:
Δ=b²-4·a·c
para o "x" temos:
$x=\frac{-b\pm\sqrt{\Delta}}{2a}$
a) 4x²-4x-35=0
Δ=(-4)²-4·4·(-35)
Δ=16+560
Δ=576
$x=\frac{-(-4)\pm\sqrt{576}}{2\cdot{4}}=\frac{4\pm24}{8}$
x'=28/8⇒7/2
x"= -20/8=⇒-5/2
b) 2x²-x-1=0
Δ=(-x)²-4·2·(-1)
Δ=1+8
Δ=9
$x=\frac{-(-1)\pm\sqrt{9}}{2\cdot{2}}=\frac{1\pm3}{4}$
x'=4/4⇒1/1⇒1
x"=-2/4⇒-1/2
c)9x²-18x-7=0
Δ=(-18)²-4·9·(-7)
Δ=324+252
Δ=576
$x=\frac{-(-18)\pm\sqrt{576}}{2\cdot{9}}=\frac{18\pm24}{18}$
x'=42/18⇒21/9⇒7/3
x"=-6/18⇒-3/9⇒-1/3
Espero ter ajudado :)