x^2-4x-91=7 eching

$$x ^ { 2 } - 4 x - 91 = 7$$

x uchun yechish

$$x=\sqrt{102}+2\approx 12,099504938$$

$$x=2-\sqrt{102}\approx -8,099504938$$

Kvadrat tenglamalaridan foydalanish qoidalari

ax^{2}+bx+c=0 shaklidagi barcha tenglamalarni kvadrat formulasi bilan yechish mumkin: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. Kvadrat formula ikki yechmni taqdim qiladi, biri ± qo'shish bo'lganda, va ikkinchisi ayiruv bo'lganda.

$$x^{2}-4x-91=7$$

Tenglamaning ikkala tarafidan 7 ni ayirish.

$$x^{2}-4x-91-7=7-7$$

O‘zidan 7 ayirilsa 0 qoladi.

$$x^{2}-4x-91-7=0$$

-91 dan 7 ni ayirish.

$$x^{2}-4x-98=0$$

Ushbu tenglama standart shaklidadir: ax^{2}+bx+c=0. Kvadrat tenglama formulasida, \frac{-b±\sqrt{b^{2}-4ac}}{2a} 1 ni a, -4 ni b va -98 ni c bilan almashtiring.

$$x=\frac{-\left(-4\right)±\sqrt{\left(-4\right)^{2}-4\left(-98\right)}}{2}$$

-4 kvadratini chiqarish.

$$x=\frac{-\left(-4\right)±\sqrt{16-4\left(-98\right)}}{2}$$

-4 ni -98 marotabaga ko'paytirish.

$$x=\frac{-\left(-4\right)±\sqrt{16+392}}{2}$$

16 ni 392 ga qo'shish.

$$x=\frac{-\left(-4\right)±\sqrt{408}}{2}$$

408 ning kvadrat ildizini chiqarish.

$$x=\frac{-\left(-4\right)±2\sqrt{102}}{2}$$

-4 ning teskarisi 4 ga teng.

$$x=\frac{4±2\sqrt{102}}{2}$$

x=\frac{4±2\sqrt{102}}{2} tenglamasini yeching, bunda ± musbat. 4 ni 2\sqrt{102} ga qo'shish.

$$x=\frac{2\sqrt{102}+4}{2}$$

4+2\sqrt{102} ni 2 ga bo'lish.

$$x=\sqrt{102}+2$$

x=\frac{4±2\sqrt{102}}{2} tenglamasini yeching, bunda ± manfiy. 4 dan 2\sqrt{102} ni ayirish.

$$x=\frac{4-2\sqrt{102}}{2}$$

4-2\sqrt{102} ni 2 ga bo'lish.

$$x=2-\sqrt{102}$$

Tenglama yechildi.

$$x=\sqrt{102}+2 x=2-\sqrt{102}$$

Kvadratni yakunlash bo'yicha qadamlar

Bu kabi kvadrat tenglamalarni kvadratni yakunlab yechish mumkin. Kvadratni yechish uchun tenglama avval ushbu shaklda bo'lishi shart: x^{2}+bx=c.

$$x^{2}-4x-91=7$$

91 ni tenglamaning ikkala tarafiga qo'shish.

$$x^{2}-4x-91-\left(-91\right)=7-\left(-91\right)$$

O‘zidan -91 ayirilsa 0 qoladi.

$$x^{2}-4x=7-\left(-91\right)$$

7 dan -91 ni ayirish.

$$x^{2}-4x=98$$

-4 ni bo‘lish, x shartining koeffitsienti, 2 ga -2 olish uchun. Keyin, -2 ning kvadratini tenglamaning ikkala tarafiga qo‘shing. Ushbu qadam tenglamaning chap qismini mukammal kvadrat sifatida hosil qiladi.

$$x^{2}-4x+\left(-2\right)^{2}=98+\left(-2\right)^{2}$$

-2 kvadratini chiqarish.

$$x^{2}-4x+4=98+4$$

98 ni 4 ga qo'shish.

$$x^{2}-4x+4=102$$

x^{2}-4x+4 omili. Odatda, x^{2}+bx+c mukammal kvadrat bo'lsa, u doimo \left(x+\frac{b}{2}\right)^{2} omil sifatida bo'lishi mumkin.

$$\left(x-2\right)^{2}=102$$

Tenglamaning ikkala tarafining kvadrat ildizini chiqarish.

$$\sqrt{\left(x-2\right)^{2}}=\sqrt{102}$$

Qisqartirish.

$$x-2=\sqrt{102} x-2=-\sqrt{102}$$

2 ni tenglamaning ikkala tarafiga qo'shish.

$$x=\sqrt{102}+2 x=2-\sqrt{102}$$