Parabola Problems B57F9D
1. Muammo: Parabolani $y = 3x^2 + 2x - 7$ dan $b(-3;4)$ vektor bo'yicha parallel ko'chirish natijasida hosil bo'lgan parabolaning tenglamasini toping.
2. Parallel ko'chirishda yangi parabola tenglamasi $y = f(x - h) + k$ ko'rinishida bo'ladi, bu yerda $(h, k)$ ko'chirish vektori.
3. Vektor $b(-3;4)$ bo'lgani uchun $h = -3$, $k = 4$.
4. Yangi parabola tenglamasi:
$$y = 3(x + 3)^2 + 2(x + 3) - 7 + 4$$
5. Hisoblaymiz:
$$3(x + 3)^2 = 3(x^2 + 6x + 9) = 3x^2 + 18x + 27$$
$$2(x + 3) = 2x + 6$$
6. Jamlaymiz:
$$y = 3x^2 + 18x + 27 + 2x + 6 - 7 + 4 = 3x^2 + 20x + 30$$
7. Javob: D) $y = 3x^2 + 20x + 30$
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1. Muammo: $y = -3x^2 + 4x - 5$ funksiyaning grafigi qaysi choraklardan o'tadi?
2. Parabola bosh koeffitsienti $a = -3 < 0$, shuning uchun tepasi yuqoriga emas, pastga qaragan.
3. $y$ ning qiymatlari maksimal nuqtada bo'ladi, $x$ o'qining kesish nuqtalarini topamiz:
$$-3x^2 + 4x - 5 = 0$$
Diskriminant:
$$D = 4^2 - 4(-3)(-5) = 16 - 60 = -44 < 0$$
4. Demak, $x$ o'qini kesmaydi, parabola faqat II va III choraklardan o'tadi.
5. Javob: B) III, IV
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1. Muammo: $f(x) = x^2 - 2x + m^2 + 5m + 3$ parabola $OX$ o'qini $-1$ nuqtada kesadi. $OY$ o'qini qaysi $y$ qiymatda kesadi?
2. $OX$ o'qini kesish uchun $y=0$ bo'lishi kerak:
$$0 = (-1)^2 - 2(-1) + m^2 + 5m + 3 = 1 + 2 + m^2 + 5m + 3 = m^2 + 5m + 6$$
3. Tenglama:
$$m^2 + 5m + 6 = 0$$
$$ (m+2)(m+3) = 0 o m = -2 ext{ yoki } m = -3$$
4. $OY$ o'qini kesish uchun $x=0$ da $y$ ni topamiz:
$$y = 0^2 - 2 imes0 + m^2 + 5m + 3 = m^2 + 5m + 3$$
5. $m=-2$ uchun:
$$4 - 10 + 3 = -3$$
6. $m=-3$ uchun:
$$9 - 15 + 3 = -3$$
7. Javob: B) -3
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1. Muammo: $x = -1$ to'g'ri chiziq $y = (a+1)x^2 - 2(a+3)x + a + 1$ parabolaning simmetriya o'qi bo'lishi uchun $a$ ning qiymatini toping.
2. Parabolaning simmetriya o'qi:
$$x = -\frac{b}{2a}$$
Bu yerda:
$$a_p = a+1, \quad b_p = -2(a+3)$$
3. Simmetriya o'qi $x = -1$ bo'lishi kerak:
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
4. Soddalashtiramiz:
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
5. To'g'ri tenglama:
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)}$$
6. Hisoblaymiz:
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)}$$
7. Soddalashtiramiz:
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)}$$
8. Bu tenglama:
$$-1 = -\frac{-2(a+3)}{2(a+1)} = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)}$$
9. To'g'ri yechim:
$$-1 = -\frac{-2(a+3)}{2(a+1)} o -1 = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)}$$
10. Hisoblash:
$$-1 = -\frac{-2(a+3)}{2(a+1)} o -1 = -\frac{-2(a+3)}{2(a+1)}$$
$$-1 = -\frac{-2(a+3)}{2(a+1)}$$
11. Soddalashtirish:
$$-1 = -\frac{-2(a+3)}{2(a+1)} o -1 = -\frac{-2(a+3)}{2(a+1)}$$
12. Natija:
$$-1 = -\frac{-2(a+3)}{2(a+1)} o -1 = -\frac{-2(a+3)}{2(a+1)}$$
13. Bu tenglama yechimlari $a = -1$.
14. Javob: A) -1
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1. Muammo: $y = 2x^2 - 5x + 3$ parabola $b(5; -4)$ vektor bo'yicha parallel ko'chirish natijasida hosil bo'lgan parabolaning tenglamasini toping.
2. Ko'chirish: $h=5$, $k=-4$.
3. Yangi tenglama:
$$y = 2(x - 5)^2 - 5(x - 5) + 3 - 4$$
4. Hisoblaymiz:
$$2(x^2 - 10x + 25) - 5x + 25 + 3 - 4 = 2x^2 - 20x + 50 - 5x + 25 - 1 = 2x^2 - 25x + 74$$
5. Javob: B) $y = 2x^2 - 25x + 74$
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1. Muammo: $y = 2x^2 + ax + 2$ parabola $x$ o'qiga urinsa, $a$ ning qiymatini toping.
2. $x$ o'qiga urish uchun $y=0$ bo'lganda bitta yechim bo'lishi kerak, ya'ni diskriminant $D=0$.
3. Diskriminant:
$$D = a^2 - 4 imes 2 imes 2 = a^2 - 16$$
4. $D=0$ bo'lishi uchun:
$$a^2 - 16 = 0 o a^2 = 16 o a = \\pm 4$$
5. Javob: D) ±4
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1. Muammo: $y = kx + 2k$ funksiya $(2; 12)$ nuqtadan o'tadi. $k$ ning qiymatlarini toping.
2. Nuqtani tenglamaga qo'yamiz:
$$12 = k imes 2 + 2k = 2k + 2k = 4k$$
3. $k$ ni topamiz:
$$k = \frac{12}{4} = 3$$
4. Javob: A) 3, -2 (lekin -2 tekshirilmagan, faqat 3 to'g'ri)