m uchun yechish
m=2\sqrt{114}+20\approx 41,354156504
m=20-2\sqrt{114}\approx -1,354156504
Baham ko'rish
Klipbordga nusxa olish
m^{2}-40m-56=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.
m=\frac{-\left(-40\right)±\sqrt{\left(-40\right)^{2}-4\left(-56\right)}}{2}
Ushbu tenglama standart shaklidadir: ax^{2}+bx+c=0. Kvadrat tenglama formulasida, \frac{-b±\sqrt{b^{2}-4ac}}{2a} 1 ni a, -40 ni b va -56 ni c bilan almashtiring.
m=\frac{-\left(-40\right)±\sqrt{1600-4\left(-56\right)}}{2}
-40 kvadratini chiqarish.
m=\frac{-\left(-40\right)±\sqrt{1600+224}}{2}
-4 ni -56 marotabaga ko'paytirish.
m=\frac{-\left(-40\right)±\sqrt{1824}}{2}
1600 ni 224 ga qo'shish.
m=\frac{-\left(-40\right)±4\sqrt{114}}{2}
1824 ning kvadrat ildizini chiqarish.
m=\frac{40±4\sqrt{114}}{2}
-40 ning teskarisi 40 ga teng.
m=\frac{4\sqrt{114}+40}{2}
m=\frac{40±4\sqrt{114}}{2} tenglamasini yeching, bunda ± musbat. 40 ni 4\sqrt{114} ga qo'shish.
m=2\sqrt{114}+20
40+4\sqrt{114} ni 2 ga bo'lish.
m=\frac{40-4\sqrt{114}}{2}
m=\frac{40±4\sqrt{114}}{2} tenglamasini yeching, bunda ± manfiy. 40 dan 4\sqrt{114} ni ayirish.
m=20-2\sqrt{114}
40-4\sqrt{114} ni 2 ga bo'lish.
m=2\sqrt{114}+20 m=20-2\sqrt{114}
Tenglama yechildi.
m^{2}-40m-56=0
Bu kabi kvadrat tenglamalarni kvadratni yakunlab yechish mumkin. Kvadratni yechish uchun tenglama avval ushbu shaklda bo'lishi shart: x^{2}+bx=c.
m^{2}-40m-56-\left(-56\right)=-\left(-56\right)
56 ni tenglamaning ikkala tarafiga qo'shish.
m^{2}-40m=-\left(-56\right)
O‘zidan -56 ayirilsa 0 qoladi.
m^{2}-40m=56
0 dan -56 ni ayirish.
m^{2}-40m+\left(-20\right)^{2}=56+\left(-20\right)^{2}
-40 ni bo‘lish, x shartining koeffitsienti, 2 ga -20 olish uchun. Keyin, -20 ning kvadratini tenglamaning ikkala tarafiga qo‘shing. Ushbu qadam tenglamaning chap qismini mukammal kvadrat sifatida hosil qiladi.
m^{2}-40m+400=56+400
-20 kvadratini chiqarish.
m^{2}-40m+400=456
56 ni 400 ga qo'shish.
\left(m-20\right)^{2}=456
m^{2}-40m+400 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(m-20\right)^{2}}=\sqrt{456}
Tenglamaning ikkala tarafining kvadrat ildizini chiqarish.
m-20=2\sqrt{114} m-20=-2\sqrt{114}
Qisqartirish.
m=2\sqrt{114}+20 m=20-2\sqrt{114}
20 ni tenglamaning ikkala tarafiga qo'shish.
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