Whakaoti i te x^2-2x-9=0

$$x ^ { 2 } - 2 x - 9 = 0$$

Whakaoti mō x

$$x=\sqrt{10}+1\approx 4.16227766$$

$$x=1-\sqrt{10}\approx -2.16227766$$

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.

$$x^{2}-2x-9=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 1 mō a, -2 mō b, me -9 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

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

Pūrua -2.

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

Whakareatia -4 ki te -9.

$$x=\frac{-\left(-2\right)±\sqrt{4+36}}{2}$$

Tāpiri 4 ki te 36.

$$x=\frac{-\left(-2\right)±\sqrt{40}}{2}$$

Tuhia te pūtakerua o te 40.

$$x=\frac{-\left(-2\right)±2\sqrt{10}}{2}$$

Ko te tauaro o -2 ko 2.

$$x=\frac{2±2\sqrt{10}}{2}$$

Nā, me whakaoti te whārite x=\frac{2±2\sqrt{10}}{2} ina he tāpiri te ±. Tāpiri 2 ki te 2\sqrt{10}.

$$x=\frac{2\sqrt{10}+2}{2}$$

Whakawehe 2+2\sqrt{10} ki te 2.

$$x=\sqrt{10}+1$$

Nā, me whakaoti te whārite x=\frac{2±2\sqrt{10}}{2} ina he tango te ±. Tango 2\sqrt{10} mai i 2.

$$x=\frac{2-2\sqrt{10}}{2}$$

Whakawehe 2-2\sqrt{10} ki te 2.

$$x=1-\sqrt{10}$$

Kua oti te whārite te whakatau.

$$x=\sqrt{10}+1 x=1-\sqrt{10}$$

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.

$$x^{2}-2x-9=0$$

Me tāpiri 9 ki ngā taha e rua o te whārite.

$$x^{2}-2x-9-\left(-9\right)=-\left(-9\right)$$

Mā te tango i te -9 i a ia ake anō ka toe ko te 0.

$$x^{2}-2x=-\left(-9\right)$$

Tango -9 mai i 0.

$$x^{2}-2x=9$$

Whakawehea te -2, te tau whakarea o te kīanga tau x, ki te 2 kia riro ai te -1. Nā, tāpiria te pūrua o te -1 ki ngā taha e rua o te whārite. Mā konei e pūrua tika tonu ai te taha mauī o te whārite.

$$x^{2}-2x+1=9+1$$

Tāpiri 9 ki te 1.

$$x^{2}-2x+1=10$$

Tauwehea te x^{2}-2x+1. Ko te tikanga, ina ko x^{2}+bx+c he pūrua tika, ka taea te tauwehe i ngā wā katoa hei \left(x+\frac{b}{2}\right)^{2}.

$$\left(x-1\right)^{2}=10$$

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

$$\sqrt{\left(x-1\right)^{2}}=\sqrt{10}$$

Whakarūnātia.

$$x-1=\sqrt{10} x-1=-\sqrt{10}$$

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

$$x=\sqrt{10}+1 x=1-\sqrt{10}$$