trabalho de matematica

EXERCICIO

a) x!x-2!=30, x pertence a N/x≥2

b)x+1!(x-1)=72, x pertence a N/x≥1

c)x!x-2!=5, x pertence a N/x≥2

Respostas

a)xx-1(x-2)(x-2)=30

x(x-1)=30

x²-x-30=0

∆=b²-4ac

∆=-1²-4(1).(-30)

∆=1+120=121

X’=-b± √∆

X’1+121=21+112=6

X’’=1-√1212=1-112=-5

b)x+1x(x-1)(x-1)=72

x²+x-72=0

∆=1²-4(1)(-72)

∆=1+278

∆=289

X’=-1±√2892

X’=-1+172

X=8

X’’=-1±√2892

X’’=-1-172

X=-9 S={(8)}

c) xx-1x-2!x-2!=5

x²-x-5=0

∆=b²-4ac

∆=(-1)²-4(1)(-5)

∆=21

X’=1±√212