Multiply by 0.4 on both sides to cancel the original 0.4 and change the 10
The answer is, y = -1/3 - 3
X²+6x+8=0
x²+2*3x+9-1=0
(x+3)²-1=0
(x+3)²-1²=0
(x+3-1)(x+3+1)=0
(x+2)(x+4)=0
x₁=-2
x₂=-4
Answer: x₁=-2, x₂=-4
EK=6, KF=6
By the Pythagorean theorem

EF≈8,48≈8
Answer: 8 units
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P.S. Hello from Russia :^)