Whakaoti i te x^2-5(-x)+7=0

$${ x }^{ 2 } -5(-x)+7=0$$

Whakaoti mō x (complex solution)

$$x=\frac{-5+\sqrt{3}i}{2}\approx -2.5+0.866025404i$$

$$x=\frac{-\sqrt{3}i-5}{2}\approx -2.5-0.866025404i$$

Ngā Upane e Whakamahi ana i te Tikanga Tātai Pūrua

Whakareatia te -1 ki te 5, ka -5.

$$x^{2}-5\left(-1\right)x+7=0$$

Whakareatia te -5 ki te -1, ka 5.

$$x^{2}+5x+7=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 1 mō a, 5 mō b, me 7 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-5±\sqrt{5^{2}-4\times 7}}{2}$$

Pūrua 5.

$$x=\frac{-5±\sqrt{25-4\times 7}}{2}$$

Whakareatia -4 ki te 7.

$$x=\frac{-5±\sqrt{25-28}}{2}$$

Tāpiri 25 ki te -28.

$$x=\frac{-5±\sqrt{-3}}{2}$$

Tuhia te pūtakerua o te -3.

$$x=\frac{-5±\sqrt{3}i}{2}$$

Nā, me whakaoti te whārite x=\frac{-5±\sqrt{3}i}{2} ina he tāpiri te ±. Tāpiri -5 ki te i\sqrt{3}.

$$x=\frac{-5+\sqrt{3}i}{2}$$

Nā, me whakaoti te whārite x=\frac{-5±\sqrt{3}i}{2} ina he tango te ±. Tango i\sqrt{3} mai i -5.

$$x=\frac{-\sqrt{3}i-5}{2}$$

Kua oti te whārite te whakatau.

$$x=\frac{-5+\sqrt{3}i}{2} x=\frac{-\sqrt{3}i-5}{2}$$

Ngā Upane mō te Whakaoti i te Pūrua

Tangohia te 7 mai i ngā taha e rua. Ko te tau i tango i te kore ka hua ko tōna korenga.

$$x^{2}-5\left(-x\right)=-7$$

Whakareatia te -1 ki te 5, ka -5.

$$x^{2}-5\left(-1\right)x=-7$$

Whakareatia te -5 ki te -1, ka 5.

$$x^{2}+5x=-7$$

Whakawehea te 5, te tau whakarea o te kīanga tau x, ki te 2 kia riro ai te \frac{5}{2}. Nā, tāpiria te pūrua o te \frac{5}{2} ki ngā taha e rua o te whārite. Mā konei e pūrua tika tonu ai te taha mauī o te whārite.

$$x^{2}+5x+\left(\frac{5}{2}\right)^{2}=-7+\left(\frac{5}{2}\right)^{2}$$

Pūruatia \frac{5}{2} mā te pūrua i te taurunga me te tauraro o te hautanga.

$$x^{2}+5x+\frac{25}{4}=-7+\frac{25}{4}$$

Tāpiri -7 ki te \frac{25}{4}.

$$x^{2}+5x+\frac{25}{4}=-\frac{3}{4}$$

Tauwehea x^{2}+5x+\frac{25}{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}.

$$\left(x+\frac{5}{2}\right)^{2}=-\frac{3}{4}$$

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

$$\sqrt{\left(x+\frac{5}{2}\right)^{2}}=\sqrt{-\frac{3}{4}}$$

Whakarūnātia.

$$x+\frac{5}{2}=\frac{\sqrt{3}i}{2} x+\frac{5}{2}=-\frac{\sqrt{3}i}{2}$$

Me tango \frac{5}{2} mai i ngā taha e rua o te whārite.

$$x=\frac{-5+\sqrt{3}i}{2} x=\frac{-\sqrt{3}i-5}{2}$$