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Se consideră expresia E(x)=(2x-1) la a doua -3(x-3)(x+2)-(x-2)(x+1)
Demonstrați că E(1)+E(1 supra 2)+E(1 supra 3)+......E(1 supra 2020)=42420





Răspundeți repede vă rog!​


Răspuns :

[tex]E(x) = (2x-1)^2-3(x-3)(x+2)-(x-2)(x+1)[/tex]

[tex]=4x^2-4x+1-3x^2+3x+18-x^2+x+2[/tex]

[tex]=21\\ \\[/tex]

[tex]E(1)+E\left(\frac{1}{2}\right)+E\left(\frac{1}{3}\right)+...+E\left(\frac{1}{2020}\right)=[/tex]

[tex]=21+21+21+\underset{\text{de 2020 ori}}{\underbrace{...}}+21\\ = 21\cdot 2020[/tex]

[tex]=\boxed{42420}[/tex]