Enrhifo
3-3\sqrt{15}\approx -8.618950039
Rhannu
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\frac{-42\left(1-\sqrt{15}\right)}{\left(1+\sqrt{15}\right)\left(1-\sqrt{15}\right)}
Mae'n rhesymoli enwadur \frac{-42}{1+\sqrt{15}} drwy luosi'r rhifiadur a'r enwadur â 1-\sqrt{15}.
\frac{-42\left(1-\sqrt{15}\right)}{1^{2}-\left(\sqrt{15}\right)^{2}}
Ystyriwch \left(1+\sqrt{15}\right)\left(1-\sqrt{15}\right). Gellir trawsnewid lluosi yn wahaniaeth rhwng sgwariau drwy ddefnyddio’r rheol: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}.
\frac{-42\left(1-\sqrt{15}\right)}{1-15}
Sgwâr 1. Sgwâr \sqrt{15}.
\frac{-42\left(1-\sqrt{15}\right)}{-14}
Tynnu 15 o 1 i gael -14.
3\left(1-\sqrt{15}\right)
Rhannu -42\left(1-\sqrt{15}\right) â -14 i gael 3\left(1-\sqrt{15}\right).
3-3\sqrt{15}
Defnyddio’r briodwedd ddosbarthu i luosi 3 â 1-\sqrt{15}.
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