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a+b=3 ab=1\left(-18\right)=-18
Whakatauwehea te kīanga mā te whakarōpū. Tuatahi, me tuhi anō te kīanga hei t^{2}+at+bt-18. Hei kimi a me b, whakaritea tētahi pūnaha kia whakaoti.
-1,18 -2,9 -3,6
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 -18.
-1+18=17 -2+9=7 -3+6=3
Tātaihia te tapeke mō ia takirua.
a=-3 b=6
Ko te otinga te takirua ka hoatu i te tapeke 3.
\left(t^{2}-3t\right)+\left(6t-18\right)
Tuhia anō te t^{2}+3t-18 hei \left(t^{2}-3t\right)+\left(6t-18\right).
t\left(t-3\right)+6\left(t-3\right)
Tauwehea te t i te tuatahi me te 6 i te rōpū tuarua.
\left(t-3\right)\left(t+6\right)
Whakatauwehea atu te kīanga pātahi t-3 mā te whakamahi i te āhuatanga tātai tohatoha.
t^{2}+3t-18=0
Ka taea te huamaha pūrua te tauwehe mā te whakamahi i te huringa ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right), ina ko x_{1} me x_{2} ngā otinga o te whārite pūrua ax^{2}+bx+c=0.
t=\frac{-3±\sqrt{3^{2}-4\left(-18\right)}}{2}
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.
t=\frac{-3±\sqrt{9-4\left(-18\right)}}{2}
Pūrua 3.
t=\frac{-3±\sqrt{9+72}}{2}
Whakareatia -4 ki te -18.
t=\frac{-3±\sqrt{81}}{2}
Tāpiri 9 ki te 72.
t=\frac{-3±9}{2}
Tuhia te pūtakerua o te 81.
t=\frac{6}{2}
Nā, me whakaoti te whārite t=\frac{-3±9}{2} ina he tāpiri te ±. Tāpiri -3 ki te 9.
t=3
Whakawehe 6 ki te 2.
t=-\frac{12}{2}
Nā, me whakaoti te whārite t=\frac{-3±9}{2} ina he tango te ±. Tango 9 mai i -3.
t=-6
Whakawehe -12 ki te 2.
t^{2}+3t-18=\left(t-3\right)\left(t-\left(-6\right)\right)
Tauwehea te kīanga taketake mā te whakamahi i te ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right). Me whakakapi te 3 mō te x_{1} me te -6 mō te x_{2}.
t^{2}+3t-18=\left(t-3\right)\left(t+6\right)
Whakamāmātia ngā kīanga katoa o te āhua p-\left(-q\right) ki te p+q.