Răspuns:
Explicație pas cu pas:
(x-3)² + (x + 2)²-2(x+1)(x-1) = x²-6x+9 +x²+4x+4 -2x²+2 =
= -2x+11
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A = {x∈ R | x-21 ≤ 3}
x-21 ≤ 3 <=> x ≤ 24 => x ∈ (-∞ ; 24]
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(4x - 5)²- 9x² = (4x - 5)²- (3x)² = (4x-5-3x)(4x-5+3x) =
= (x-5)(7x-5)