Whakaoti i te 2x^2+6x+8=0

$$2 x ^ { 2 } + 6 x + 8 = 0$$

Whakaoti mō x (complex solution)

$$x=\frac{-3+\sqrt{7}i}{2}\approx -1.5+1.322875656i$$

$$x=\frac{-\sqrt{7}i-3}{2}\approx -1.5-1.322875656i$$

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.

$$2x^{2}+6x+8=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 2 mō a, 6 mō b, me 8 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-6±\sqrt{6^{2}-4\times 2\times 8}}{2\times 2}$$

Pūrua 6.

$$x=\frac{-6±\sqrt{36-4\times 2\times 8}}{2\times 2}$$

Whakareatia -4 ki te 2.

$$x=\frac{-6±\sqrt{36-8\times 8}}{2\times 2}$$

Whakareatia -8 ki te 8.

$$x=\frac{-6±\sqrt{36-64}}{2\times 2}$$

Tāpiri 36 ki te -64.

$$x=\frac{-6±\sqrt{-28}}{2\times 2}$$

Tuhia te pūtakerua o te -28.

$$x=\frac{-6±2\sqrt{7}i}{2\times 2}$$

Whakareatia 2 ki te 2.

$$x=\frac{-6±2\sqrt{7}i}{4}$$

Nā, me whakaoti te whārite x=\frac{-6±2\sqrt{7}i}{4} ina he tāpiri te ±. Tāpiri -6 ki te 2i\sqrt{7}.

$$x=\frac{-6+2\sqrt{7}i}{4}$$

Whakawehe -6+2i\sqrt{7} ki te 4.

$$x=\frac{-3+\sqrt{7}i}{2}$$

Nā, me whakaoti te whārite x=\frac{-6±2\sqrt{7}i}{4} ina he tango te ±. Tango 2i\sqrt{7} mai i -6.

$$x=\frac{-2\sqrt{7}i-6}{4}$$

Whakawehe -6-2i\sqrt{7} ki te 4.

$$x=\frac{-\sqrt{7}i-3}{2}$$

Kua oti te whārite te whakatau.

$$x=\frac{-3+\sqrt{7}i}{2} x=\frac{-\sqrt{7}i-3}{2}$$

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.

$$2x^{2}+6x+8=0$$

Me tango 8 mai i ngā taha e rua o te whārite.

$$2x^{2}+6x+8-8=-8$$

Mā te tango i te 8 i a ia ake anō ka toe ko te 0.

$$2x^{2}+6x=-8$$

Whakawehea ngā taha e rua ki te 2.

$$\frac{2x^{2}+6x}{2}=-\frac{8}{2}$$

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

$$x^{2}+\frac{6}{2}x=-\frac{8}{2}$$

Whakawehe 6 ki te 2.

$$x^{2}+3x=-\frac{8}{2}$$

Whakawehe -8 ki te 2.

$$x^{2}+3x=-4$$

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.

$$x^{2}+3x+\left(\frac{3}{2}\right)^{2}=-4+\left(\frac{3}{2}\right)^{2}$$

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

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

Tāpiri -4 ki te \frac{9}{4}.

$$x^{2}+3x+\frac{9}{4}=-\frac{7}{4}$$

Tauwehea x^{2}+3x+\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}.

$$\left(x+\frac{3}{2}\right)^{2}=-\frac{7}{4}$$

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

$$\sqrt{\left(x+\frac{3}{2}\right)^{2}}=\sqrt{-\frac{7}{4}}$$

Whakarūnātia.

$$x+\frac{3}{2}=\frac{\sqrt{7}i}{2} x+\frac{3}{2}=-\frac{\sqrt{7}i}{2}$$

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

$$x=\frac{-3+\sqrt{7}i}{2} x=\frac{-\sqrt{7}i-3}{2}$$