1. a) x²=16
x={-4,4}
b)x²+1,44=1,69
x²=0,25
x={-1/4, 1/4}
c)x²+5=1
x²=-4
x={-2i, 2i}
2. 3(x²+2x+1)=27
x²+2x+1=9
x²+2x-8=0
Δ=4+4*8=36
x₁=(-2+6)/2=2
x₂=(-2-6)/2=-4
=> x={-4,2} ∈ R
3. 4x²+4x+1-1+2x-x²+1=4-2x
3x²+6x+1-4+2x=0
3x²+8x-3=0
Δ= 64+36=100
x₁=1
x₂=-9
4.
x²+x²+2x+1+x²-2x+1=x²+4x+4+x²-4x+4+3
3x²+2=2x²+11
x²=9
x={-3,3}
5. 4(4x²-20x+25)-(9x²+6x+1)=0
16x²-80x+100-9x²-6x-1=0
7x²-86x+99=0
Δ=7396-2772=4624
x₁=11
x₂=9/7
