Question

1)Resolva as equações a sequir. a)10y-5(1+y)-3(2y-2)-20. d)x(x+4)+x(x+2)=2x2+12. e)(x-5_10) + (1-2x_5)=(3-x_4) f)4x(x+6)-x2=5x2

Answer 1

a)10y-5(1+y)-3(2y-2)-20
10y-5-5y-6y+6-20
-y-19

d)x(x+4)+x(x+2)=2x2+12
x²+4x+x²+2x=4x+12
x²+x²+2x=12
2x²+2x=12
x²+x=6
x²+x-6=0
a=1 ; b=1; c=-6
Δ=b²-4.a.c
Δ=(1)²-4.(1).(-6)
Δ=1+24
Δ=25
x= -b + ou - √Δ / 2.a
x=-(1) + ou - √25 / 2.(1)
x=-1 + ou - 5 / 2
x¹= -1+5 =4/2=2
x² -1-5=  -6/2=-3



f)4x(x+6)-x2=5x2
4x²+24-2x=10x
4x²+22=10x
2x²+11=5x
2x²+11-5x=0
2x²+6x=0
a=2 ; b=6 c=-0
Δ=b²-4.a.c
Δ=(6)²-4(20).(-0)
Δ=36+0
Δ=36

x= -b + ou - √Δ  / 2.a
x= -(6) + ou - √36 /  2.(2)
x= -6 + ou - 6 /8
x¹= -6 +6=0 /8=0
x²= -6-6=12/2=6/2=3
                8/2=4/=2