Question

E urgent! Dau coroana!​

Answer 1

25.x -1/x=3 ridicăm ambii membri la pătrat

x²-2x×1/x+(1/x)²=9

x²+1/x²=9+2

a)x²+1/x²=11

b) x -1/x=3 ridicăm ambii membri la a treia

x³-3x²×1/x+3x×1/x²-1/x³=27

x³-3x+3×1/x-1/x³=27

x³-3(x-1/x)-1/x³=27

x³-1/x³-3×3=27

b)x³-1/x³=36

x -1/x=3 ridicăm ambii membri la a 5a

(x-1/x)(x⁴+x³1/x+x²1/x²+x1/x³+1/x⁴)=243

3(x⁴+1/x⁴+x²+1+1/x²)=243

x⁴+1/x⁴+11+1=81

c)x⁴+1/x⁴=69

26.x+y=4 ,xy=3

a) (x+y)²=4²

(x+y)²=16

b) x²+y²=(x²+y²+2xy)-2xy=(x+y)²-2xy=

4²-2×3=16-6=10

c) (x-y)²=x²-2xy+y²+2xy-2xy=(x+y)²-4xy=

4²-4×3=16-12=4

d) 1/x-1/y=(y-x)/xy= de la c) x-y=2

1/x-1/y=2/3