x uchun yechish
x = -\frac{9}{2} = -4\frac{1}{2} = -4,5
x=6
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Klipbordga nusxa olish
2\left(x^{2}+6\right)-21=3\left(x+15\right)
Tenglamaning ikkala tarafini 6 ga, 3,2 ning eng kichik karralisiga ko‘paytiring.
2x^{2}+12-21=3\left(x+15\right)
2 ga x^{2}+6 ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
2x^{2}-9=3\left(x+15\right)
-9 olish uchun 12 dan 21 ni ayirish.
2x^{2}-9=3x+45
3 ga x+15 ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
2x^{2}-9-3x=45
Ikkala tarafdan 3x ni ayirish.
2x^{2}-9-3x-45=0
Ikkala tarafdan 45 ni ayirish.
2x^{2}-54-3x=0
-54 olish uchun -9 dan 45 ni ayirish.
2x^{2}-3x-54=0
Polinomni standart shaklga keltirish uchun uni qayta tartiblang. Shartlarni eng yuqoridan eng pastki qiymat ko'rsatgichiga joylashtirish.
a+b=-3 ab=2\left(-54\right)=-108
Tenglamani yechish uchun guruhlash orqali chap qoʻl tomonni faktorlang. Avvalo, chap qoʻl tomon 2x^{2}+ax+bx-54 sifatida qayta yozilishi kerak. a va b ni topish uchun yechiladigan tizimni sozlang.
1,-108 2,-54 3,-36 4,-27 6,-18 9,-12
ab manfiy boʻlganda, a va b da qarama-qarshi belgilar bor. a+b manfiy boʻlganda, manfiy sonda musbatga nisbatdan kattaroq mutlaq qiymat bor. -108-mahsulotni beruvchi bunday butun juftliklarni roʻyxat qiling.
1-108=-107 2-54=-52 3-36=-33 4-27=-23 6-18=-12 9-12=-3
Har bir juftlik yigʻindisini hisoblang.
a=-12 b=9
Yechim – -3 yigʻindisini beruvchi juftlik.
\left(2x^{2}-12x\right)+\left(9x-54\right)
2x^{2}-3x-54 ni \left(2x^{2}-12x\right)+\left(9x-54\right) sifatida qaytadan yozish.
2x\left(x-6\right)+9\left(x-6\right)
Birinchi guruhda 2x ni va ikkinchi guruhda 9 ni faktordan chiqaring.
\left(x-6\right)\left(2x+9\right)
Distributiv funktsiyasidan foydalangan holda x-6 umumiy terminini chiqaring.
x=6 x=-\frac{9}{2}
Tenglamani yechish uchun x-6=0 va 2x+9=0 ni yeching.
2\left(x^{2}+6\right)-21=3\left(x+15\right)
Tenglamaning ikkala tarafini 6 ga, 3,2 ning eng kichik karralisiga ko‘paytiring.
2x^{2}+12-21=3\left(x+15\right)
2 ga x^{2}+6 ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
2x^{2}-9=3\left(x+15\right)
-9 olish uchun 12 dan 21 ni ayirish.
2x^{2}-9=3x+45
3 ga x+15 ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
2x^{2}-9-3x=45
Ikkala tarafdan 3x ni ayirish.
2x^{2}-9-3x-45=0
Ikkala tarafdan 45 ni ayirish.
2x^{2}-54-3x=0
-54 olish uchun -9 dan 45 ni ayirish.
2x^{2}-3x-54=0
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=\frac{-\left(-3\right)±\sqrt{\left(-3\right)^{2}-4\times 2\left(-54\right)}}{2\times 2}
Ushbu tenglama standart shaklidadir: ax^{2}+bx+c=0. Kvadrat tenglama formulasida, \frac{-b±\sqrt{b^{2}-4ac}}{2a} 2 ni a, -3 ni b va -54 ni c bilan almashtiring.
x=\frac{-\left(-3\right)±\sqrt{9-4\times 2\left(-54\right)}}{2\times 2}
-3 kvadratini chiqarish.
x=\frac{-\left(-3\right)±\sqrt{9-8\left(-54\right)}}{2\times 2}
-4 ni 2 marotabaga ko'paytirish.
x=\frac{-\left(-3\right)±\sqrt{9+432}}{2\times 2}
-8 ni -54 marotabaga ko'paytirish.
x=\frac{-\left(-3\right)±\sqrt{441}}{2\times 2}
9 ni 432 ga qo'shish.
x=\frac{-\left(-3\right)±21}{2\times 2}
441 ning kvadrat ildizini chiqarish.
x=\frac{3±21}{2\times 2}
-3 ning teskarisi 3 ga teng.
x=\frac{3±21}{4}
2 ni 2 marotabaga ko'paytirish.
x=\frac{24}{4}
x=\frac{3±21}{4} tenglamasini yeching, bunda ± musbat. 3 ni 21 ga qo'shish.
x=6
24 ni 4 ga bo'lish.
x=-\frac{18}{4}
x=\frac{3±21}{4} tenglamasini yeching, bunda ± manfiy. 3 dan 21 ni ayirish.
x=-\frac{9}{2}
\frac{-18}{4} ulushini 2 ni chiqarib, bekor qilish hisobiga eng past shartlarga kamaytiring.
x=6 x=-\frac{9}{2}
Tenglama yechildi.
2\left(x^{2}+6\right)-21=3\left(x+15\right)
Tenglamaning ikkala tarafini 6 ga, 3,2 ning eng kichik karralisiga ko‘paytiring.
2x^{2}+12-21=3\left(x+15\right)
2 ga x^{2}+6 ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
2x^{2}-9=3\left(x+15\right)
-9 olish uchun 12 dan 21 ni ayirish.
2x^{2}-9=3x+45
3 ga x+15 ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
2x^{2}-9-3x=45
Ikkala tarafdan 3x ni ayirish.
2x^{2}-3x=45+9
9 ni ikki tarafga qo’shing.
2x^{2}-3x=54
54 olish uchun 45 va 9'ni qo'shing.
\frac{2x^{2}-3x}{2}=\frac{54}{2}
Ikki tarafini 2 ga bo‘ling.
x^{2}-\frac{3}{2}x=\frac{54}{2}
2 ga bo'lish 2 ga ko'paytirishni bekor qiladi.
x^{2}-\frac{3}{2}x=27
54 ni 2 ga bo'lish.
x^{2}-\frac{3}{2}x+\left(-\frac{3}{4}\right)^{2}=27+\left(-\frac{3}{4}\right)^{2}
-\frac{3}{2} ni bo‘lish, x shartining koeffitsienti, 2 ga -\frac{3}{4} olish uchun. Keyin, -\frac{3}{4} ning kvadratini tenglamaning ikkala tarafiga qo‘shing. Ushbu qadam tenglamaning chap qismini mukammal kvadrat sifatida hosil qiladi.
x^{2}-\frac{3}{2}x+\frac{9}{16}=27+\frac{9}{16}
Kasrning ham suratini, ham maxrajini kvadratga ko'paytirib -\frac{3}{4} kvadratini chiqarish.
x^{2}-\frac{3}{2}x+\frac{9}{16}=\frac{441}{16}
27 ni \frac{9}{16} ga qo'shish.
\left(x-\frac{3}{4}\right)^{2}=\frac{441}{16}
x^{2}-\frac{3}{2}x+\frac{9}{16} omili. Odatda, x^{2}+bx+c mukammal kvadrat bo'lsa, u doimo \left(x+\frac{b}{2}\right)^{2} omil sifatida bo'lishi mumkin.
\sqrt{\left(x-\frac{3}{4}\right)^{2}}=\sqrt{\frac{441}{16}}
Tenglamaning ikkala tarafining kvadrat ildizini chiqarish.
x-\frac{3}{4}=\frac{21}{4} x-\frac{3}{4}=-\frac{21}{4}
Qisqartirish.
x=6 x=-\frac{9}{2}
\frac{3}{4} ni tenglamaning ikkala tarafiga qo'shish.
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