Whakaoti i te 3x^2+9x-30=0

$$3 x ^ { 2 } + 9 x - 30 = 0$$

Whakaoti mō x

$$x=-5$$

$$x=2$$

Ngā Upane Whakamahi Tauwehe Mā te Whakarōpū

Whakawehea ngā taha e rua ki te 3.

$$x^{2}+3x-10=0$$

Hei whakaoti i te whārite, whakatauwehea te taha mauī mā te whakarōpū. Tuatahi, me tuhi anō te taha mauī hei x^{2}+ax+bx-10. Hei kimi a me b, whakaritea tētahi pūnaha kia whakaoti.

$$a+b=3 ab=1\left(-10\right)=-10$$

I te mea kua tōraro te ab, he tauaro ngā tohu o a me b. I te mea kua tōrunga te a+b, he nui ake te uara pū o te tau tōrunga i tō te tōraro. Whakarārangitia ngā tau tōpū takirua pērā katoa ka hoatu i te hua -10.

$$-1,10 -2,5$$

Tātaihia te tapeke mō ia takirua.

$$-1+10=9 -2+5=3$$

Ko te otinga te takirua ka hoatu i te tapeke 3.

$$a=-2 b=5$$

Tuhia anō te x^{2}+3x-10 hei \left(x^{2}-2x\right)+\left(5x-10\right).

$$\left(x^{2}-2x\right)+\left(5x-10\right)$$

Tauwehea te x i te tuatahi me te 5 i te rōpū tuarua.

$$x\left(x-2\right)+5\left(x-2\right)$$

Whakatauwehea atu te kīanga pātahi x-2 mā te whakamahi i te āhuatanga tātai tohatoha.

$$\left(x-2\right)\left(x+5\right)$$

Hei kimi otinga whārite, me whakaoti te x-2=0 me te x+5=0.

$$x=2 x=-5$$

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.

$$3x^{2}+9x-30=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 3 mō a, 9 mō b, me -30 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-9±\sqrt{9^{2}-4\times 3\left(-30\right)}}{2\times 3}$$

Pūrua 9.

$$x=\frac{-9±\sqrt{81-4\times 3\left(-30\right)}}{2\times 3}$$

Whakareatia -4 ki te 3.

$$x=\frac{-9±\sqrt{81-12\left(-30\right)}}{2\times 3}$$

Whakareatia -12 ki te -30.

$$x=\frac{-9±\sqrt{81+360}}{2\times 3}$$

Tāpiri 81 ki te 360.

$$x=\frac{-9±\sqrt{441}}{2\times 3}$$

Tuhia te pūtakerua o te 441.

$$x=\frac{-9±21}{2\times 3}$$

Whakareatia 2 ki te 3.

$$x=\frac{-9±21}{6}$$

Nā, me whakaoti te whārite x=\frac{-9±21}{6} ina he tāpiri te ±. Tāpiri -9 ki te 21.

$$x=\frac{12}{6}$$

Whakawehe 12 ki te 6.

$$x=2$$

Nā, me whakaoti te whārite x=\frac{-9±21}{6} ina he tango te ±. Tango 21 mai i -9.

$$x=-\frac{30}{6}$$

Whakawehe -30 ki te 6.

$$x=-5$$

Kua oti te whārite te whakatau.

$$x=2 x=-5$$

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.

$$3x^{2}+9x-30=0$$

Me tāpiri 30 ki ngā taha e rua o te whārite.

$$3x^{2}+9x-30-\left(-30\right)=-\left(-30\right)$$

Mā te tango i te -30 i a ia ake anō ka toe ko te 0.

$$3x^{2}+9x=-\left(-30\right)$$

Tango -30 mai i 0.

$$3x^{2}+9x=30$$

Whakawehea ngā taha e rua ki te 3.

$$\frac{3x^{2}+9x}{3}=\frac{30}{3}$$

Mā te whakawehe ki te 3 ka wetekia te whakareanga ki te 3.

$$x^{2}+\frac{9}{3}x=\frac{30}{3}$$

Whakawehe 9 ki te 3.

$$x^{2}+3x=\frac{30}{3}$$

Whakawehe 30 ki te 3.

$$x^{2}+3x=10$$

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.

$$x^{2}+3x+\left(\frac{3}{2}\right)^{2}=10+\left(\frac{3}{2}\right)^{2}$$

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

$$x^{2}+3x+\frac{9}{4}=10+\frac{9}{4}$$

Tāpiri 10 ki te \frac{9}{4}.

$$x^{2}+3x+\frac{9}{4}=\frac{49}{4}$$

Tauwehea te x^{2}+3x+\frac{9}{4}. 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}.

$$\left(x+\frac{3}{2}\right)^{2}=\frac{49}{4}$$

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

$$\sqrt{\left(x+\frac{3}{2}\right)^{2}}=\sqrt{\frac{49}{4}}$$

Whakarūnātia.

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

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

$$x=2 x=-5$$