Odpowiedź:
d) (2x+1)² - 9(x-1)² = 4 - x
4x²+4x+1 -9(x²-2x+1) = 4-x
4x²+4x+1-9x²+18x-9=4-x
-5x²+23x-12=0
Δ = 23²-4*(-5)*(-12)=529-240=289
√Δ=17
x₁=-23+17/2*(-5)=-6/-10= 3/5
x₂=-23-17/2*(-5)=-40/-10= 4
e) x²-2x+1+2(x²-6x+9)=18-10x
x²-2x+1+2x²-12x+18=18-10x
3x²-4x+1=0
Δ=(-4)²-4*3*1=16-12=4
√Δ=2
x₁=4+2/2*3=6/6= 1
x₂=4-2/2*3=2/6 = 1/3
f) 4x²+20x+25-(4x²-20x+25)=3x²+41x-4
4x²+20x+25-4x²+20x-25=3x²+41x-4
3x²+x-4 = 0
Δ = 1 -4*3*(-4)=1+48=49
√Δ=7
x₁=-1+7/2*3=-8/6 = -4/3
x₂=-1-7/2*3=6/6 = 1
