x uchun yechish
x = -\frac{14}{3} = -4\frac{2}{3} \approx -4,666666667
x=2
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30-\left(x+3\right)x=\left(x+2\right)\left(2x+1\right)
x qiymati -3,-2 qiymatlaridan birortasiga teng bo‘lmaydi, chunki nolga bo‘lish mumkin emas. Tenglamaning ikkala tarafini \left(x+2\right)\left(x+3\right) ga, x^{2}+5x+6,x+2,x+3 ning eng kichik karralisiga ko‘paytiring.
30-\left(x^{2}+3x\right)=\left(x+2\right)\left(2x+1\right)
x+3 ga x ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
30-x^{2}-3x=\left(x+2\right)\left(2x+1\right)
x^{2}+3x teskarisini topish uchun har birining teskarisini toping.
30-x^{2}-3x=2x^{2}+5x+2
x+2 ga 2x+1 ni ko‘paytirish orqali distributiv xususiyatdan foydalaning va ifoda sifatida birlashtiring.
30-x^{2}-3x-2x^{2}=5x+2
Ikkala tarafdan 2x^{2} ni ayirish.
30-3x^{2}-3x=5x+2
-3x^{2} ni olish uchun -x^{2} va -2x^{2} ni birlashtirish.
30-3x^{2}-3x-5x=2
Ikkala tarafdan 5x ni ayirish.
30-3x^{2}-8x=2
-8x ni olish uchun -3x va -5x ni birlashtirish.
30-3x^{2}-8x-2=0
Ikkala tarafdan 2 ni ayirish.
28-3x^{2}-8x=0
28 olish uchun 30 dan 2 ni ayirish.
-3x^{2}-8x+28=0
Polinomni standart shaklga keltirish uchun uni qayta tartiblang. Shartlarni eng yuqoridan eng pastki qiymat ko'rsatgichiga joylashtirish.
a+b=-8 ab=-3\times 28=-84
Tenglamani yechish uchun guruhlash orqali chap qoʻl tomonni faktorlang. Avvalo, chap qoʻl tomon -3x^{2}+ax+bx+28 sifatida qayta yozilishi kerak. a va b ni topish uchun yechiladigan tizimni sozlang.
1,-84 2,-42 3,-28 4,-21 6,-14 7,-12
ab manfiy boʻlganda, a va b da qarama-qarshi belgilar bor. a+b manfiy boʻlganda, manfiy sonda musbatga nisbatdan kattaroq mutlaq qiymat bor. -84-mahsulotni beruvchi bunday butun juftliklarni roʻyxat qiling.
1-84=-83 2-42=-40 3-28=-25 4-21=-17 6-14=-8 7-12=-5
Har bir juftlik yigʻindisini hisoblang.
a=6 b=-14
Yechim – -8 yigʻindisini beruvchi juftlik.
\left(-3x^{2}+6x\right)+\left(-14x+28\right)
-3x^{2}-8x+28 ni \left(-3x^{2}+6x\right)+\left(-14x+28\right) sifatida qaytadan yozish.
3x\left(-x+2\right)+14\left(-x+2\right)
Birinchi guruhda 3x ni va ikkinchi guruhda 14 ni faktordan chiqaring.
\left(-x+2\right)\left(3x+14\right)
Distributiv funktsiyasidan foydalangan holda -x+2 umumiy terminini chiqaring.
x=2 x=-\frac{14}{3}
Tenglamani yechish uchun -x+2=0 va 3x+14=0 ni yeching.
30-\left(x+3\right)x=\left(x+2\right)\left(2x+1\right)
x qiymati -3,-2 qiymatlaridan birortasiga teng bo‘lmaydi, chunki nolga bo‘lish mumkin emas. Tenglamaning ikkala tarafini \left(x+2\right)\left(x+3\right) ga, x^{2}+5x+6,x+2,x+3 ning eng kichik karralisiga ko‘paytiring.
30-\left(x^{2}+3x\right)=\left(x+2\right)\left(2x+1\right)
x+3 ga x ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
30-x^{2}-3x=\left(x+2\right)\left(2x+1\right)
x^{2}+3x teskarisini topish uchun har birining teskarisini toping.
30-x^{2}-3x=2x^{2}+5x+2
x+2 ga 2x+1 ni ko‘paytirish orqali distributiv xususiyatdan foydalaning va ifoda sifatida birlashtiring.
30-x^{2}-3x-2x^{2}=5x+2
Ikkala tarafdan 2x^{2} ni ayirish.
30-3x^{2}-3x=5x+2
-3x^{2} ni olish uchun -x^{2} va -2x^{2} ni birlashtirish.
30-3x^{2}-3x-5x=2
Ikkala tarafdan 5x ni ayirish.
30-3x^{2}-8x=2
-8x ni olish uchun -3x va -5x ni birlashtirish.
30-3x^{2}-8x-2=0
Ikkala tarafdan 2 ni ayirish.
28-3x^{2}-8x=0
28 olish uchun 30 dan 2 ni ayirish.
-3x^{2}-8x+28=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(-8\right)±\sqrt{\left(-8\right)^{2}-4\left(-3\right)\times 28}}{2\left(-3\right)}
Ushbu tenglama standart shaklidadir: ax^{2}+bx+c=0. Kvadrat tenglama formulasida, \frac{-b±\sqrt{b^{2}-4ac}}{2a} -3 ni a, -8 ni b va 28 ni c bilan almashtiring.
x=\frac{-\left(-8\right)±\sqrt{64-4\left(-3\right)\times 28}}{2\left(-3\right)}
-8 kvadratini chiqarish.
x=\frac{-\left(-8\right)±\sqrt{64+12\times 28}}{2\left(-3\right)}
-4 ni -3 marotabaga ko'paytirish.
x=\frac{-\left(-8\right)±\sqrt{64+336}}{2\left(-3\right)}
12 ni 28 marotabaga ko'paytirish.
x=\frac{-\left(-8\right)±\sqrt{400}}{2\left(-3\right)}
64 ni 336 ga qo'shish.
x=\frac{-\left(-8\right)±20}{2\left(-3\right)}
400 ning kvadrat ildizini chiqarish.
x=\frac{8±20}{2\left(-3\right)}
-8 ning teskarisi 8 ga teng.
x=\frac{8±20}{-6}
2 ni -3 marotabaga ko'paytirish.
x=\frac{28}{-6}
x=\frac{8±20}{-6} tenglamasini yeching, bunda ± musbat. 8 ni 20 ga qo'shish.
x=-\frac{14}{3}
\frac{28}{-6} ulushini 2 ni chiqarib, bekor qilish hisobiga eng past shartlarga kamaytiring.
x=-\frac{12}{-6}
x=\frac{8±20}{-6} tenglamasini yeching, bunda ± manfiy. 8 dan 20 ni ayirish.
x=2
-12 ni -6 ga bo'lish.
x=-\frac{14}{3} x=2
Tenglama yechildi.
30-\left(x+3\right)x=\left(x+2\right)\left(2x+1\right)
x qiymati -3,-2 qiymatlaridan birortasiga teng bo‘lmaydi, chunki nolga bo‘lish mumkin emas. Tenglamaning ikkala tarafini \left(x+2\right)\left(x+3\right) ga, x^{2}+5x+6,x+2,x+3 ning eng kichik karralisiga ko‘paytiring.
30-\left(x^{2}+3x\right)=\left(x+2\right)\left(2x+1\right)
x+3 ga x ni ko'paytirish orqali distributiv xususiyatdan foydalanish.
30-x^{2}-3x=\left(x+2\right)\left(2x+1\right)
x^{2}+3x teskarisini topish uchun har birining teskarisini toping.
30-x^{2}-3x=2x^{2}+5x+2
x+2 ga 2x+1 ni ko‘paytirish orqali distributiv xususiyatdan foydalaning va ifoda sifatida birlashtiring.
30-x^{2}-3x-2x^{2}=5x+2
Ikkala tarafdan 2x^{2} ni ayirish.
30-3x^{2}-3x=5x+2
-3x^{2} ni olish uchun -x^{2} va -2x^{2} ni birlashtirish.
30-3x^{2}-3x-5x=2
Ikkala tarafdan 5x ni ayirish.
30-3x^{2}-8x=2
-8x ni olish uchun -3x va -5x ni birlashtirish.
-3x^{2}-8x=2-30
Ikkala tarafdan 30 ni ayirish.
-3x^{2}-8x=-28
-28 olish uchun 2 dan 30 ni ayirish.
\frac{-3x^{2}-8x}{-3}=-\frac{28}{-3}
Ikki tarafini -3 ga bo‘ling.
x^{2}+\left(-\frac{8}{-3}\right)x=-\frac{28}{-3}
-3 ga bo'lish -3 ga ko'paytirishni bekor qiladi.
x^{2}+\frac{8}{3}x=-\frac{28}{-3}
-8 ni -3 ga bo'lish.
x^{2}+\frac{8}{3}x=\frac{28}{3}
-28 ni -3 ga bo'lish.
x^{2}+\frac{8}{3}x+\left(\frac{4}{3}\right)^{2}=\frac{28}{3}+\left(\frac{4}{3}\right)^{2}
\frac{8}{3} ni bo‘lish, x shartining koeffitsienti, 2 ga \frac{4}{3} olish uchun. Keyin, \frac{4}{3} ning kvadratini tenglamaning ikkala tarafiga qo‘shing. Ushbu qadam tenglamaning chap qismini mukammal kvadrat sifatida hosil qiladi.
x^{2}+\frac{8}{3}x+\frac{16}{9}=\frac{28}{3}+\frac{16}{9}
Kasrning ham suratini, ham maxrajini kvadratga ko'paytirib \frac{4}{3} kvadratini chiqarish.
x^{2}+\frac{8}{3}x+\frac{16}{9}=\frac{100}{9}
Umumiy maxrajni topib va hisoblovchini qo'shish orqali \frac{28}{3} ni \frac{16}{9} ga qo'shing. So'ngra agar imkoni bo'lsa kasrni eng kam shartga qisqartiring.
\left(x+\frac{4}{3}\right)^{2}=\frac{100}{9}
x^{2}+\frac{8}{3}x+\frac{16}{9} 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{4}{3}\right)^{2}}=\sqrt{\frac{100}{9}}
Tenglamaning ikkala tarafining kvadrat ildizini chiqarish.
x+\frac{4}{3}=\frac{10}{3} x+\frac{4}{3}=-\frac{10}{3}
Qisqartirish.
x=2 x=-\frac{14}{3}
Tenglamaning ikkala tarafidan \frac{4}{3} ni ayirish.
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