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Question

Phân tích đa thức thành nhân tử:

$x^2-x-121$

GIẢI GIÚP MK NAH! THANKS M.N!!!!!

phạm đức lâm · Accepted Answer

$x^2$ - $x$ - 121

= ($x^2$ - $2.x.\frac{1}{2}$ + $\frac{1}{4}$ ) - $\frac{1}{4}$ - 121

= ($x$ - $\frac{1}{2}$ )² - $\frac{485}{4}$

= ($x$ - $\frac{1}{2}$ - $\frac{\sqrt{485}}{2}$ ) ($x$ - $\frac{1}{2}$ + $\frac{\sqrt{485}}{2}$ )

= ($x$ - $\frac{1+\sqrt{485}}{2}$ ) ($x$ - $\frac{1-\sqrt{485}}{2}$ )

Câu trả lời:

$x^2$ - $x$ - 121

= ($x^2$ - $2.x.\frac{1}{2}$ + $\frac{1}{4}$ ) - $\frac{1}{4}$ - 121

= ($x$ - $\frac{1}{2}$ )² - $\frac{485}{4}$

= ($x$ - $\frac{1}{2}$ - $\frac{\sqrt{485}}{2}$ ) ($x$ - $\frac{1}{2}$ + $\frac{\sqrt{485}}{2}$ )

= ($x$ - $\frac{1+\sqrt{485}}{2}$ ) ($x$ - $\frac{1-\sqrt{485}}{2}$ )

Riio Riyuko · Answer

$x^2-x-121$

$=\left(x^2-2.x.\frac{1}{2}+\frac{1}{4}\right)-\frac{1}{4}-121$

$=\left(x-\frac{1}{2}\right)^2-\frac{485}{4}$

$=\left(x-\frac{1}{2}-\frac{\sqrt{485}}{2}\right)\left(x-\frac{1}{2}+\frac{\sqrt{485}}{2}\right)$

$=\left(x-\frac{1+\sqrt{485}}{2}\right)\left(x-\frac{1-\sqrt{485}}{2}\right)$

Câu trả lời:

$x^2-x-121$

$=\left(x^2-2.x.\frac{1}{2}+\frac{1}{4}\right)-\frac{1}{4}-121$

$=\left(x-\frac{1}{2}\right)^2-\frac{485}{4}$

$=\left(x-\frac{1}{2}-\frac{\sqrt{485}}{2}\right)\left(x-\frac{1}{2}+\frac{\sqrt{485}}{2}\right)$

$=\left(x-\frac{1+\sqrt{485}}{2}\right)\left(x-\frac{1-\sqrt{485}}{2}\right)$