Question

!!! VA ROG AJUTAȚI-MĂ E FOARTE URGENT!!!

Answer 1

4. a.

$a= (\frac{1}{\sqrt{3} } + \frac{2}{2\sqrt{3} } + \frac{3}{3\sqrt{3} } + \frac{4}{4\sqrt{3} } )$·$\frac{3}{2}$

Se simplifica 2 cu 2, 3 cu 3 si 4 cu 4, apoi rationalizam fiecare fractie.

a=4·$\frac{\sqrt{3} }{3}$·$\frac{3}{2}$

Se simplificam 3 cu 3 si 2 cu 4.

$a=2\sqrt{3}$

b.

$b=\frac{\sqrt{676-100} }{\sqrt{400-256} }$  ·$\frac{3\sqrt{2} }{2}$

$b=\frac{\sqrt{576} }{\sqrt{144} }$ ·$\frac{3\sqrt{2} }{2}$

$b=\frac{24}{12}$ · $\frac{3\sqrt{2} }{2}$

$b=3\sqrt{2}$

(a+b) |a-b|=($3\sqrt{2} +2\sqrt{3}$) ($3\sqrt{2} - 2\sqrt{3}$)= 18-12=6

5.

E(x)= x(9x²-12x+4)-2(3x³-2x²-6x²+4x)+x³-4x²+4x

E(x)= 9x³-12x²+4x-6x³+16x²-8x+x³-4x²+4x

E(x)= 4x³

E(-a)= 4(-a)³= -4a³

E(a)= 4a³

E(-a)+ E(a)= -4a³+4a³= 0