Whakaoti i te 2x^2-15x=-7

$$2 x ^ { 2 } - 15 x = - 7$$

Whakaoti mō x

$$x=\frac{1}{2}=0.5$$

$$x=7$$

Ngā Upane Whakamahi Tauwehe Mā te Whakarōpū

Me tāpiri te 7 ki ngā taha e rua.

$$2x^{2}-15x+7=0$$

Hei whakaoti i te whārite, whakatauwehea te taha mauī mā te whakarōpū. Tuatahi, me tuhi anō te taha mauī hei 2x^{2}+ax+bx+7. Hei kimi a me b, whakaritea tētahi pūnaha kia whakaoti.

$$a+b=-15 ab=2\times 7=14$$

I te mea kua tōrunga te ab, he ōrite te tohu o a me b. I te mea kua tōraro te a+b, he tōraro hoki a a me b. Whakarārangitia ngā tau tōpū takirua pērā katoa ka hoatu i te hua 14.

$$-1,-14 -2,-7$$

Tātaihia te tapeke mō ia takirua.

$$-1-14=-15 -2-7=-9$$

Ko te otinga te takirua ka hoatu i te tapeke -15.

$$a=-14 b=-1$$

Tuhia anō te 2x^{2}-15x+7 hei \left(2x^{2}-14x\right)+\left(-x+7\right).

$$\left(2x^{2}-14x\right)+\left(-x+7\right)$$

Tauwehea te 2x i te tuatahi me te -1 i te rōpū tuarua.

$$2x\left(x-7\right)-\left(x-7\right)$$

Whakatauwehea atu te kīanga pātahi x-7 mā te whakamahi i te āhuatanga tātai tohatoha.

$$\left(x-7\right)\left(2x-1\right)$$

Hei kimi otinga whārite, me whakaoti te x-7=0 me te 2x-1=0.

$$x=7 x=\frac{1}{2}$$

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.

$$2x^{2}-15x=-7$$

Me tāpiri 7 ki ngā taha e rua o te whārite.

$$2x^{2}-15x-\left(-7\right)=-7-\left(-7\right)$$

Mā te tango i te -7 i a ia ake anō ka toe ko te 0.

$$2x^{2}-15x-\left(-7\right)=0$$

Tango -7 mai i 0.

$$2x^{2}-15x+7=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 2 mō a, -15 mō b, me 7 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-\left(-15\right)±\sqrt{\left(-15\right)^{2}-4\times 2\times 7}}{2\times 2}$$

Pūrua -15.

$$x=\frac{-\left(-15\right)±\sqrt{225-4\times 2\times 7}}{2\times 2}$$

Whakareatia -4 ki te 2.

$$x=\frac{-\left(-15\right)±\sqrt{225-8\times 7}}{2\times 2}$$

Whakareatia -8 ki te 7.

$$x=\frac{-\left(-15\right)±\sqrt{225-56}}{2\times 2}$$

Tāpiri 225 ki te -56.

$$x=\frac{-\left(-15\right)±\sqrt{169}}{2\times 2}$$

Tuhia te pūtakerua o te 169.

$$x=\frac{-\left(-15\right)±13}{2\times 2}$$

Ko te tauaro o -15 ko 15.

$$x=\frac{15±13}{2\times 2}$$

Whakareatia 2 ki te 2.

$$x=\frac{15±13}{4}$$

Nā, me whakaoti te whārite x=\frac{15±13}{4} ina he tāpiri te ±. Tāpiri 15 ki te 13.

$$x=\frac{28}{4}$$

Whakawehe 28 ki te 4.

$$x=7$$

Nā, me whakaoti te whārite x=\frac{15±13}{4} ina he tango te ±. Tango 13 mai i 15.

$$x=\frac{2}{4}$$

Whakahekea te hautanga \frac{2}{4} ki ōna wāhi pāpaku rawa mā te tango me te whakakore i te 2.

$$x=\frac{1}{2}$$

Kua oti te whārite te whakatau.

$$x=7 x=\frac{1}{2}$$

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.

$$2x^{2}-15x=-7$$

Whakawehea ngā taha e rua ki te 2.

$$\frac{2x^{2}-15x}{2}=-\frac{7}{2}$$

Mā te whakawehe ki te 2 ka wetekia te whakareanga ki te 2.

$$x^{2}-\frac{15}{2}x=-\frac{7}{2}$$

Whakawehea te -\frac{15}{2}, te tau whakarea o te kīanga tau x, ki te 2 kia riro ai te -\frac{15}{4}. Nā, tāpiria te pūrua o te -\frac{15}{4} ki ngā taha e rua o te whārite. Mā konei e pūrua tika tonu ai te taha mauī o te whārite.

$$x^{2}-\frac{15}{2}x+\left(-\frac{15}{4}\right)^{2}=-\frac{7}{2}+\left(-\frac{15}{4}\right)^{2}$$

Pūruatia -\frac{15}{4} mā te pūrua i te taurunga me te tauraro o te hautanga.

$$x^{2}-\frac{15}{2}x+\frac{225}{16}=-\frac{7}{2}+\frac{225}{16}$$

Tāpiri -\frac{7}{2} ki te \frac{225}{16} mā te kimi i te tauraro pātahi me te tāpiri i ngā taurunga. Ka whakaiti i te hautanga ki ngā kīanga tau iti rawa e taea ana.

$$x^{2}-\frac{15}{2}x+\frac{225}{16}=\frac{169}{16}$$

Tauwehea x^{2}-\frac{15}{2}x+\frac{225}{16}. 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}.

$$\left(x-\frac{15}{4}\right)^{2}=\frac{169}{16}$$

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

$$\sqrt{\left(x-\frac{15}{4}\right)^{2}}=\sqrt{\frac{169}{16}}$$

Whakarūnātia.

$$x-\frac{15}{4}=\frac{13}{4} x-\frac{15}{4}=-\frac{13}{4}$$

Me tāpiri \frac{15}{4} ki ngā taha e rua o te whārite.

$$x=7 x=\frac{1}{2}$$