Question

Resolva cada equação a seguir:
a) x2+2x-15=O

b) 4x2-3x-1=O

c) 15x2-45x=O

d) 4x2-5x=O

Answer 1

A)
 
x² + 2x - 15 = 0
a=1 , b=2 , c = -15

Δ=b² - 4(ac)

Δ=(2)² - 4 (1*(-15))
Δ=8

x = -b+-Δ/2a

X1 = -2+8/2 = 3
X2 = -2 -8 / 2 = -5
===============================================

B)

4x² -3x - 1 = 0

a=4 b = -3 c = -1

Δ = (-3)² - 4(-1*(-4)) => Δ=25 = 5
X1=3+5/2 = 4
X2=3-5/2=-1
===========================================

C)

15x² - 45x = 0

a=15 b = -45 c = 0

Δ(45)² - 4(15*0)
Δ=45

X1=45+45/2*45 = 1
X2 = 45-45/2*45 = 0