Whakaoti i te b^2+2b-5=0

$$b ^ { 2 } + 2 b - 5 = 0$$

Whakaoti mō b

$$b=\sqrt{6}-1\approx 1.449489743$$

$$b=-\sqrt{6}-1\approx -3.449489743$$

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.

$$b^{2}+2b-5=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 1 mō a, 2 mō b, me -5 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$b=\frac{-2±\sqrt{2^{2}-4\left(-5\right)}}{2}$$

Pūrua 2.

$$b=\frac{-2±\sqrt{4-4\left(-5\right)}}{2}$$

Whakareatia -4 ki te -5.

$$b=\frac{-2±\sqrt{4+20}}{2}$$

Tāpiri 4 ki te 20.

$$b=\frac{-2±\sqrt{24}}{2}$$

Tuhia te pūtakerua o te 24.

$$b=\frac{-2±2\sqrt{6}}{2}$$

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

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

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

$$b=\sqrt{6}-1$$

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

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

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

$$b=-\sqrt{6}-1$$

Kua oti te whārite te whakatau.

$$b=\sqrt{6}-1 b=-\sqrt{6}-1$$

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.

$$b^{2}+2b-5=0$$

Me tāpiri 5 ki ngā taha e rua o te whārite.

$$b^{2}+2b-5-\left(-5\right)=-\left(-5\right)$$

Mā te tango i te -5 i a ia ake anō ka toe ko te 0.

$$b^{2}+2b=-\left(-5\right)$$

Tango -5 mai i 0.

$$b^{2}+2b=5$$

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.

$$b^{2}+2b+1^{2}=5+1^{2}$$

Pūrua 1.

$$b^{2}+2b+1=5+1$$

Tāpiri 5 ki te 1.

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

Tauwehea b^{2}+2b+1. 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}.

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

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

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

Whakarūnātia.

$$b+1=\sqrt{6} b+1=-\sqrt{6}$$

Me tango 1 mai i ngā taha e rua o te whārite.

$$b=\sqrt{6}-1 b=-\sqrt{6}-1$$