Whakaoti i te x^2+5x+25/4=81/4

$$x ^ { 2 } + 5 x + \frac { 25 } { 4 } = \frac { 81 } { 4 }$$

Whakaoti mō x

$$x=-7$$

$$x=2$$

Ngā Upane Whakamahi Tauwehe

Tangohia te \frac{81}{4} mai i ngā taha e rua.

$$x^{2}+5x+\frac{25}{4}-\frac{81}{4}=0$$

Tangohia te \frac{81}{4} i te \frac{25}{4}, ka -14.

$$x^{2}+5x-14=0$$

Hei whakaoti i te whārite, whakatauwehea te x^{2}+5x-14 mā te whakamahi i te tātai x^{2}+\left(a+b\right)x+ab=\left(x+a\right)\left(x+b\right). Hei kimi a me b, whakaritea tētahi pūnaha kia whakaoti.

$$a+b=5 ab=-14$$

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 -14.

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

Tātaihia te tapeke mō ia takirua.

$$-1+14=13 -2+7=5$$

Ko te otinga te takirua ka hoatu i te tapeke 5.

$$a=-2 b=7$$

Me tuhi anō te kīanga whakatauwehe \left(x+a\right)\left(x+b\right) mā ngā uara i tātaihia.

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

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

$$x=2 x=-7$$

Ngā Upane Whakamahi Tauwehe Mā te Whakarōpū

Tangohia te \frac{81}{4} mai i ngā taha e rua.

$$x^{2}+5x+\frac{25}{4}-\frac{81}{4}=0$$

Tangohia te \frac{81}{4} i te \frac{25}{4}, ka -14.

$$x^{2}+5x-14=0$$

Hei whakaoti i te whārite, whakatauwehea te taha mauī mā te whakarōpū. Tuatahi, me tuhi anō te taha mauī hei x^{2}+ax+bx-14. Hei kimi a me b, whakaritea tētahi pūnaha kia whakaoti.

$$a+b=5 ab=1\left(-14\right)=-14$$

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 -14.

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

Tātaihia te tapeke mō ia takirua.

$$-1+14=13 -2+7=5$$

Ko te otinga te takirua ka hoatu i te tapeke 5.

$$a=-2 b=7$$

Tuhia anō te x^{2}+5x-14 hei \left(x^{2}-2x\right)+\left(7x-14\right).

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

Tauwehea te x i te tuatahi me te 7 i te rōpū tuarua.

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

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

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

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

$$x=2 x=-7$$

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.

$$x^{2}+5x+\frac{25}{4}=\frac{81}{4}$$

Me tango \frac{81}{4} mai i ngā taha e rua o te whārite.

$$x^{2}+5x+\frac{25}{4}-\frac{81}{4}=\frac{81}{4}-\frac{81}{4}$$

Mā te tango i te \frac{81}{4} i a ia ake anō ka toe ko te 0.

$$x^{2}+5x+\frac{25}{4}-\frac{81}{4}=0$$

Tango \frac{81}{4} mai i \frac{25}{4} mā te kimi i te tauraro pātahi me te tango i ngā taurunga, ka whakaiti i te hautanga ki ngā kīanga tau iti rawa e taea ana.

$$x^{2}+5x-14=0$$

Kei te āhua arowhānui tēnei whārite: ax^{2}+bx+c=0. Me whakakapi 1 mō a, 5 mō b, me -14 mō c i te tikanga tātai pūrua, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-5±\sqrt{5^{2}-4\left(-14\right)}}{2}$$

Pūrua 5.

$$x=\frac{-5±\sqrt{25-4\left(-14\right)}}{2}$$

Whakareatia -4 ki te -14.

$$x=\frac{-5±\sqrt{25+56}}{2}$$

Tāpiri 25 ki te 56.

$$x=\frac{-5±\sqrt{81}}{2}$$

Tuhia te pūtakerua o te 81.

$$x=\frac{-5±9}{2}$$

Nā, me whakaoti te whārite x=\frac{-5±9}{2} ina he tāpiri te ±. Tāpiri -5 ki te 9.

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

Whakawehe 4 ki te 2.

$$x=2$$

Nā, me whakaoti te whārite x=\frac{-5±9}{2} ina he tango te ±. Tango 9 mai i -5.

$$x=-\frac{14}{2}$$

Whakawehe -14 ki te 2.

$$x=-7$$

Kua oti te whārite te whakatau.

$$x=2 x=-7$$

Ngā Upane mō te Whakaoti i te Pūrua

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}.

$$\left(x+\frac{5}{2}\right)^{2}=\frac{81}{4}$$

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

$$\sqrt{\left(x+\frac{5}{2}\right)^{2}}=\sqrt{\frac{81}{4}}$$

Whakarūnātia.

$$x+\frac{5}{2}=\frac{9}{2} x+\frac{5}{2}=-\frac{9}{2}$$

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

$$x=2 x=-7$$