Question

Am nevoie urgent de rezolvare dau maximul de puncte !Corana

Answer 1

xero-urile functieri, adica valorile lui x  pt care f(x)=0
-2x²-4x+5/2=0
-4x²-8x+5=0
4x²+8x-5=0
Δ=64+80=144
√Δ=12
x1,2=(-8+-12)/8
x1=-20/8=-5/2
x2=4/8=1/2

b)f(x) ≥) intre radacini sermn contrar lui -2, adica -

x∈[-5/2;1/2]

2x+3=-2x²-4x+5/2=0
2x²+6x+3-5/2=0
2x²+6x+1/2=0
4x²+12x+1=0

Δ=144-16=128
√Δ=√128=8√2
x1,2=(-12+8√2)/8= (-3+-2√2)/2

f(x1) =2x1 +3=-3-2√2+3=-2√2

f(x2) =2x2+3=-3+2√2+3= 2√2

(x1, f(x1) )=( (-3-2√2)/2; -2√2)
(x2; f(x2))=((-3+2√2);2√2)

3
C.E.
12x²-2x-2≥0
6x²-x-1≥0
x∈(-∞;x1]∪[x2;∞)
Δ=1+24=25
√Δ=5
 x1,2= (1+-5)/12
x1=-4/12=-1/3
x2=6/12=1/2
x∈(-∞;-1/3]∪[1/2;∞)=D
 √(12x²-2x-2)=0
x1==1/3∈D
x2=1/2∈D


x²-4=0
x3=-2; x4=2


4. Fie p si d ,cantitaile in tone din primul si din, respectiv, al doilea tip de ingrasamant
 avem relatia
p*15/100+d*21/100=(p+d)*18/100
p+d=1

sau
15p+21d=18(p+d)
p+d=1
 la bunul simt, 18 fiind m a , a lui 15 si 21 rezulta cantitati egale din p si d deci p=d=0,5

totusi sa calculam folsind metoda substitutiei, d=1-p
15p +21(1-p)=18(1-p+p)
15p+21-21p=18
-6p=-3
6p=3
p=3/6=0,5⇒d=1-05=0,5