(2,1x – 1,2)^2 – 0,25 = 0 Lm cho mk cách theo hằng đẳng thức nhé 20/10/2021 Bởi Gabriella (2,1x – 1,2)^2 – 0,25 = 0 Lm cho mk cách theo hằng đẳng thức nhé
Đáp án: `S={17/21,1/3}` Giải thích các bước giải: `(2,1x-1,2)^2-0,25=0` `<=>100.(2,1x-1,2)^2-25=0` `<=>(21x-12)^2-25=0` `<=>(21x-12-5)(21x-12+5)=0` `<=>(21x-17)(21x-7)=0` `<=>` \(\left[ \begin{array}{l}21x=17\\21x=7\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=\dfrac{17}{21}\\x=\dfrac{1}{3}\end{array} \right.\) Vậy `S={17/21,1/3}` Bình luận
`\text{~~Holi~~}` `(2,1x-1,2)^2-0,25=0` `-> (21/10 x-6/5)^2-1/4=0` `-> (21/10 x-6/5)^2=1/4` `-> 21/10 x-6/5=±1/2` `->`\(\left[ \begin{array}{l}\dfrac{21}{10}x-\dfrac{6}{5}=-\dfrac{1}{2}\\\dfrac{21}{10}x-\dfrac{6}{5}=\dfrac{1}{2}\end{array} \right.\) `->`\(\left[ \begin{array}{l}x=\dfrac{1}{3}\\x=\dfrac{17}{21}\end{array} \right.\) Vậy `S={1/3,17/21}` Bình luận
Đáp án:
`S={17/21,1/3}`
Giải thích các bước giải:
`(2,1x-1,2)^2-0,25=0`
`<=>100.(2,1x-1,2)^2-25=0`
`<=>(21x-12)^2-25=0`
`<=>(21x-12-5)(21x-12+5)=0`
`<=>(21x-17)(21x-7)=0`
`<=>` \(\left[ \begin{array}{l}21x=17\\21x=7\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=\dfrac{17}{21}\\x=\dfrac{1}{3}\end{array} \right.\)
Vậy `S={17/21,1/3}`
`\text{~~Holi~~}`
`(2,1x-1,2)^2-0,25=0`
`-> (21/10 x-6/5)^2-1/4=0`
`-> (21/10 x-6/5)^2=1/4`
`-> 21/10 x-6/5=±1/2`
`->`\(\left[ \begin{array}{l}\dfrac{21}{10}x-\dfrac{6}{5}=-\dfrac{1}{2}\\\dfrac{21}{10}x-\dfrac{6}{5}=\dfrac{1}{2}\end{array} \right.\)
`->`\(\left[ \begin{array}{l}x=\dfrac{1}{3}\\x=\dfrac{17}{21}\end{array} \right.\)
Vậy `S={1/3,17/21}`