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Calculati : a) (4x-1)^2-(x-3)(x+5)
b) (5-4x)(4x+5)+(4x-3)^2
c) (7x+2)(2-7x)+(6x-1)^2



Răspuns :

a) 16x^2-8x+1-(x^2-3x+5x-15) = 16x^2-8x+1-x^2-2x+15 = 15x^2-6x+16

b)folosesti formula (a+b)(a-b)=a^2-b^2 si obtii : 25-16x^2+16x^2-24x+19 = 25-24x+9 = -24x+34