Question

-a la a doua -3a=4
a la a doua -a=12

Answer 1

a²-3a=4
a²-3a-4=0
Δ=9+16=25
a₁=(3-5)/2=-2/2=-1
a₂=(3+5)/2=8/2=4
a∈{-1,4}

a²-a=12
a²-a-12=0
Δ=1+48=49
a₁=(1-7)/2=-6/2=-3
a₂=(1+7)/2=8/2=4
a∈{-3,4}