Whakaoti i te 2b^2+6b-1=2

$$2 b ^ { 2 } + 6 b - 1 = 2$$

Whakaoti mō b

$$b=\frac{\sqrt{15}-3}{2}\approx 0.436491673$$

$$b=\frac{-\sqrt{15}-3}{2}\approx -3.436491673$$

Ngā Upane e Whakamahi ana i te Tikanga Tātai Pūrua

Ko ngā whārite katoa o te āhua ax^{2}+bx+c=0 ka taea te whakaoti mā te whakamahi i te tikanga tātai pūrua: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. E rua ngā otinga ka puta i te tikanga tātai pūrua, ko tētahi ina he tāpiri a ±, ā, ko tētahi ina he tango.

$$2b^{2}+6b-1=2$$

Me tango 2 mai i ngā taha e rua o te whārite.

$$2b^{2}+6b-1-2=2-2$$

Mā te tango i te 2 i a ia ake anō ka toe ko te 0.

$$2b^{2}+6b-1-2=0$$

Tango 2 mai i -1.

$$2b^{2}+6b-3=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 2 mō a, 6 mō b, me -3 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$b=\frac{-6±\sqrt{6^{2}-4\times 2\left(-3\right)}}{2\times 2}$$

Pūrua 6.

$$b=\frac{-6±\sqrt{36-4\times 2\left(-3\right)}}{2\times 2}$$

Whakareatia -4 ki te 2.

$$b=\frac{-6±\sqrt{36-8\left(-3\right)}}{2\times 2}$$

Whakareatia -8 ki te -3.

$$b=\frac{-6±\sqrt{36+24}}{2\times 2}$$

Tāpiri 36 ki te 24.

$$b=\frac{-6±\sqrt{60}}{2\times 2}$$

Tuhia te pūtakerua o te 60.

$$b=\frac{-6±2\sqrt{15}}{2\times 2}$$

Whakareatia 2 ki te 2.

$$b=\frac{-6±2\sqrt{15}}{4}$$

Nā, me whakaoti te whārite b=\frac{-6±2\sqrt{15}}{4} ina he tāpiri te ±. Tāpiri -6 ki te 2\sqrt{15}.

$$b=\frac{2\sqrt{15}-6}{4}$$

Whakawehe -6+2\sqrt{15} ki te 4.

$$b=\frac{\sqrt{15}-3}{2}$$

Nā, me whakaoti te whārite b=\frac{-6±2\sqrt{15}}{4} ina he tango te ±. Tango 2\sqrt{15} mai i -6.

$$b=\frac{-2\sqrt{15}-6}{4}$$

Whakawehe -6-2\sqrt{15} ki te 4.

$$b=\frac{-\sqrt{15}-3}{2}$$

Kua oti te whārite te whakatau.

$$b=\frac{\sqrt{15}-3}{2} b=\frac{-\sqrt{15}-3}{2}$$

Ngā Upane mō te Whakaoti i te Pūrua

Ko ngā whārite pūrua pēnei i tēnei nā ka taea te whakaoti mā te whakaoti i te pūrua. Hei whakaoti i te pūrua, ko te whārite me mātua tuhi ki te āhua x^{2}+bx=c.

$$2b^{2}+6b-1=2$$

Me tāpiri 1 ki ngā taha e rua o te whārite.

$$2b^{2}+6b-1-\left(-1\right)=2-\left(-1\right)$$

Mā te tango i te -1 i a ia ake anō ka toe ko te 0.

$$2b^{2}+6b=2-\left(-1\right)$$

Tango -1 mai i 2.

$$2b^{2}+6b=3$$

Whakawehea ngā taha e rua ki te 2.

$$\frac{2b^{2}+6b}{2}=\frac{3}{2}$$

Mā te whakawehe ki te 2 ka wetekia te whakareanga ki te 2.

$$b^{2}+\frac{6}{2}b=\frac{3}{2}$$

Whakawehe 6 ki te 2.

$$b^{2}+3b=\frac{3}{2}$$

Whakawehea te 3, te tau whakarea o te kīanga tau x, ki te 2 kia riro ai te \frac{3}{2}. Nā, tāpiria te pūrua o te \frac{3}{2} ki ngā taha e rua o te whārite. Mā konei e pūrua tika tonu ai te taha mauī o te whārite.

$$b^{2}+3b+\left(\frac{3}{2}\right)^{2}=\frac{3}{2}+\left(\frac{3}{2}\right)^{2}$$

Pūruatia \frac{3}{2} mā te pūrua i te taurunga me te tauraro o te hautanga.

$$b^{2}+3b+\frac{9}{4}=\frac{3}{2}+\frac{9}{4}$$

Tāpiri \frac{3}{2} ki te \frac{9}{4} mā te kimi i te tauraro pātahi me te tāpiri i ngā taurunga. Ka whakaiti i te hautanga ki ngā kīanga tau iti rawa e taea ana.

$$b^{2}+3b+\frac{9}{4}=\frac{15}{4}$$

Tauwehea b^{2}+3b+\frac{9}{4}. Ko te tikanga pūnoa, ina ko x^{2}+bx+c he pūrua tika pūrua tika pū, ka taea taua mea te tauwehea i ngā wā katoa hei \left(x+\frac{b}{2}\right)^{2}.

$$\left(b+\frac{3}{2}\right)^{2}=\frac{15}{4}$$

Tuhia te pūtakerua o ngā taha e rua o te whārite.

$$\sqrt{\left(b+\frac{3}{2}\right)^{2}}=\sqrt{\frac{15}{4}}$$

Whakarūnātia.

$$b+\frac{3}{2}=\frac{\sqrt{15}}{2} b+\frac{3}{2}=-\frac{\sqrt{15}}{2}$$

Me tango \frac{3}{2} mai i ngā taha e rua o te whārite.

$$b=\frac{\sqrt{15}-3}{2} b=\frac{-\sqrt{15}-3}{2}$$