Whakaoti i te (1)x^2-3x-2=0

$$( 1 ) x ^ { 2 } - 3 x - 2 = 0$$

Whakaoti mō x

$$x = \frac{\sqrt{17} + 3}{2} \approx 3.561552813$$

$$x=\frac{3-\sqrt{17}}{2}\approx -0.561552813$$

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.

$$x^{2}-3x-2=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 1 mō a, -3 mō b, me -2 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

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

Pūrua -3.

$$x=\frac{-\left(-3\right)±\sqrt{9-4\left(-2\right)}}{2}$$

Whakareatia -4 ki te -2.

$$x=\frac{-\left(-3\right)±\sqrt{9+8}}{2}$$

Tāpiri 9 ki te 8.

$$x=\frac{-\left(-3\right)±\sqrt{17}}{2}$$

Ko te tauaro o -3 ko 3.

$$x=\frac{3±\sqrt{17}}{2}$$

Nā, me whakaoti te whārite x=\frac{3±\sqrt{17}}{2} ina he tāpiri te ±. Tāpiri 3 ki te \sqrt{17}.

$$x=\frac{\sqrt{17}+3}{2}$$

Nā, me whakaoti te whārite x=\frac{3±\sqrt{17}}{2} ina he tango te ±. Tango \sqrt{17} mai i 3.

$$x=\frac{3-\sqrt{17}}{2}$$

Kua oti te whārite te whakatau.

$$x=\frac{\sqrt{17}+3}{2} x=\frac{3-\sqrt{17}}{2}$$

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.

$$x^{2}-3x-2=0$$

Me tāpiri 2 ki ngā taha e rua o te whārite.

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

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

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

Tango -2 mai i 0.

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

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.

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

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

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

Tāpiri 2 ki te \frac{9}{4}.

$$x^{2}-3x+\frac{9}{4}=\frac{17}{4}$$

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}.

$$\left(x-\frac{3}{2}\right)^{2}=\frac{17}{4}$$

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

$$\sqrt{\left(x-\frac{3}{2}\right)^{2}}=\sqrt{\frac{17}{4}}$$

Whakarūnātia.

$$x-\frac{3}{2}=\frac{\sqrt{17}}{2} x-\frac{3}{2}=-\frac{\sqrt{17}}{2}$$

Me tāpiri \frac{3}{2} ki ngā taha e rua o te whārite.

$$x=\frac{\sqrt{17}+3}{2} x=\frac{3-\sqrt{17}}{2}$$