56
12
pirobiT,
Z
[
\
]
]
]
]
a
2
+a>0
2
a
2
–7a–4<0, saidanac a∈(0;4).
14
y=kx
2
–6x+7 funqciis grafiks ara aqvs saerTo wertili abscisaTa RerZTan,
Tu
kx
2
–6x+7 kvadratul samwevrs ara aqvs nuli _ D<0, 9–7k<0, k∈
(
9
7; +∞
)
.
16
D
4=k
2
+2k+2 dadebiTia nebismieri k-sTvis. amitom, funqcias aqvs ori nuli
nebismieri k-sTvis.
17
a) marTkuTxedis gverdebia x da 40–x, farTobi S=x(40–x).
b) S=–x
2
+40x=–(x–20)
2
+400. funqcia udides mniSvnelobas aRwevs, roca x=20. maSin
S=400. Tu gamoviyenebT geometriul mosazrebebs, maSin x-is saZebni mniSvnelobaa
funqciis grafikis _ parabolis wveros abscisa. x= 40
2 =20. am wertilSi S=400.
18
nakveTis gverdebi aRvniSnoT x da (60–x)-iT. pirobiT farTobi udidesia.
S=–
x
2
+60x kvadratuli funqcia udides mniSvnelobas aRwevs, roca x= 60
2 =30. maSin
S=900.
19
marTkuTxedis gverdebi aRvniSnoT x da
(
a2 – x
)
-iT. S=–x
2
+ a2 x. me–18 amocanis
msgavsad vRebulobT: funqcia udides mniSvnelobas aRwevs, roca x= – a
2⋅(–2) =
a
4 , anu
marTkuTxedi kvadratia. am sami amocanis ganxilvis Semdeg kidev erTxel SevajamebT
miRebul Sedegs:
erTi da imave perimetris mqone marTkuTxedebidan udidesi farTobi
kvadrats aqvs.
20
x sT-is Semdeg horizontalur RerZze moZravi sxeuli 0-dan daSorebuli
iqneba (5+40x)km-iT, vertikalur RerZze moZravi sxeuli _ (12–60x)km-iT. piTagoras
Teoremis gamoyenebiT gamovTvaloT maT Soris manZili:
√
(5+40x)
2
+(12–60x)
2
.
vTqvaT, y=(40x+5)
2
+(12–60
x)
2
,
y=5200
x
2
–1040x+169 kvadratuli funqcia umcires mniSvnelobas aRwevs, roca
x= 1040
2⋅5200=
1
10 (sT).
pasuxi: 6 wuTis Semdeg.
22
b) Z
[
\
]]
]]
x≥0
√
x –3≠0
2
x
2
–29x+104≥0, saidanac x∈[0;6,5]∪[8;9)∪(9;+∞).
d)
Z
[
\
]
]
]
]
x(x+1)
x–2 ≥0
x–4≠0, saidanac
x∈[–1;0]∪(2;4)∪(4;+∞).
57
sakontrolo wera
SearCieT swori pasuxi:
1. cnobilia, rom a(x
2
–4)(x+3)≥0 utolobis amonaxsnTa simravlea
(–∞;–3]∪[–2;2]. maSin
1) a>0
2) a=0
3) a<0
4) a nebismieria.
2. 2x
2
+5x–3
x
≥0 utolobis amonaxsnTa simravlea
1) (–∞; –3]∪(0;0,5]
2) [–3; 0)∪[0,5; +∞)
3) (–∞; –3)∪[0;0,5)
4) (–3; 0]∪(0,5; +∞).
3.
(
x+1)
2
(x–5)(x–0,5)≤0 utolobis amonaxsnTa simravlea
1) [0,5;5]
2) [–1;0,5]∪{5}
3) (–∞;–1)∪(–1;0,5)∪(5;+∞)
4) [0,5;5]∪{–1}.
4.
Z
[
\
]
]
]
]
4x
2
–4x+1≥0
x
2
–4x>0 utolobaTa sistemis amonaxsnTa simravlea
1)
[
12; +∞
)
2) (–∞; 0)∪(4;+ ∞) da x=12
3) (–∞; 0)∪(4; +∞) 4) (0;4).
5.
Z
[
\
]
]
]
]
x
2
+x≤0
x
2
–ax≤0 sistemas aqvs erTaderTi amonaxsni
1) Tu
a<0
2) mxolod maSin, roca a=0
3) mxolod maSin, roca a>0
4) Tu a≥0.
6. y=
√
x
2
–9 +
√
4–x
2
funqciis gansazRvris area
1) (–3;–2)∪(2;3)
2) ∅
3) (–∞;–3)∪(3;+∞)
4) (–2;2).
amoxseniT amocanebi:
7. amoxseniT utoloba: x
3x+2 <
–1
x–1.
8. vTqvaT, kvadratis ori mopirdapire gverdidan TiToeulis sigrZe 2 sm-iT
gavzardeT, danarCeni ori gverdidan TiToeulis sigrZe _ 1 sm-iT SevamcireT.
miRebuli marTkuTxedis farTobi mocemuli kvadratis farTobze meti aRmoCnda.
ipoveT kvadratis gverdis SesaZlo umciresi mTeli mniSvneloba.
pasuxebi da miTiTebebi:
1. a<0.
2. x∈[–3; 0)∪
[
1
2; +∞
).
3. x∈[0,5;5]∪{–1}.
4. I utolobas akmayofilebs nebismieri x, amitom sistemis amonaxsnTa simravle
emTxveva II utolobis amonaxsnTa simravles: (–∞;0)∪(4;+∞)
5. a≥0
6.
Z
[
\
]
]
]
]
x
2
–9≥0
4–
x
2
≥
0 sistemas ara aqvs amonaxsni.
pasuxi: ∅.