Question

As avea nevoie de ex 3 și 5.Va mulțumesc

Answer 1

$3) \\ \\ a + \frac{1}{a} = 4 \: | ^{2} \\ \\ (a + \frac{1}{a})^{2} = {4}^{2} \\ \\ {a}^{2} + 2 \times a \times \frac{1}{a} + \frac{1}{ {a}^{2} } = 16 \\ \\ {a}^{2} + 2 + \frac{1}{ {a}^{2} } = 16 \\ \\ {a}^{2} + \frac{1}{ {a}^{2} } = 14 \\ \\ 5) \\ \\ {4x}^{2} + {9y}^{2} - 4x + 12y + 5 = {4x}^{2} - 4x + 1 + {9y}^{2} + 12y + 4 = (( {2x})^{2} - 2 \times 2x + 1) + ((3y)^{2} + 2 \times 3y \times 2 + {2}^{2}) = (2x - 1)^{2} + (3y + 2)^{2} = 0 \\ \\ Cum \: (2x - 1)^{2},(3y + 2)≥0,Oricare \: ar \: fi \: x,y \: din \: R = > 2x - 1 = 3y + 2 = 0 \: de \: unde \: x = \frac{1}{2} \: si \: y = - \frac{2}{3}$

Answer 2

Salut,

Ex:3

a+(1/a)=4 |*²

(a+1/a)²=4²

a²+2(a*1/a)+(1/a)²=16

a²+2+(1/a²)=16

a²+(1/a²)=16-2

a²+(1/a²)=14.

Raspuns:C)14.

Ex:5

4x²+9y²-4x+12y+5=0

4x²-4x+1+9y²+12y+4=0

(2x-1)²+(3y+2)²=0

2x-1=3y+2=0

x=1/2

y=-2/3.

Raspuns:a)x=1/2 si y=-2/3.

Bafta!