bài 1 C=7^4.3-7^3/7^4.6-7^3.2 Bài2 c, (2x+1).(x^2-1/4)=0 22/11/2021 Bởi Alaia bài 1 C=7^4.3-7^3/7^4.6-7^3.2 Bài2 c, (2x+1).(x^2-1/4)=0
Giải thích các bước giải: Bài `1``C=(7^4 . 3-7^3)/(7^4 . 6-7^3 . 2)``C=(7^3 .7 .3-7^3 .1)/(7^3 .7 .6-7^3 .2)``C=(7^3 .21 -7^3 .1)/(7^3 . 42-7^3 .2)``C=(7^3.(21-1))/(7^3.(42-2))``C=(7^3 . 20 )/(7^3 .40)``C=(7^3 .20)/(7^3 .2 .20)``C=1/2`Bài `2``(2x+1).(x^2-1/4)=0``=>`\(\left[ \begin{array}{l}2x+1=0\\x^2 -\dfrac{1}{4}=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}2x=0+1\\x^2=0+\dfrac{1}{4}\end{array} \right.\) `=>`\(\left[ \begin{array}{l}2x=1\\x^2=\dfrac{1}{4}\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=1:2\\x^2=(±\dfrac{1}{2})^2\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=\dfrac{1}{2}\\x=±\dfrac{1}{2}\end{array} \right.\) Bình luận
Đáp án: Bài `1: 1/2` Bài `2:` \(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{array} \right.\) Giải thích các bước giải: Bài `1:` `C=(7^4 . 3 – 7^3 ) / ( 7^4 . 6 – 7^3 . 2 ) ` `= ( 7^3 . ( 7 . 3 – 1 )) / ( 7^3 . ( 7 . 6 – 2))` `= ( 7^3 . 20 ) / (7^3 . 40 )` `= 20 / 40 = 1/2` Bài `2:` `c) ( 2x + 1 ) ( x^2 – 1/4 ) = 0` `=>` \(\left[ \begin{array}{l}2x+1=0\\x^2-\dfrac{1}{4}=0\end{array} \right.\) `=>` \(\left[ \begin{array}{l}2x=-1\\x^2=\dfrac{1}{4}\end{array} \right.\) `=>` \(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{array} \right.\) Bình luận
Giải thích các bước giải:
Bài `1`
`C=(7^4 . 3-7^3)/(7^4 . 6-7^3 . 2)`
`C=(7^3 .7 .3-7^3 .1)/(7^3 .7 .6-7^3 .2)`
`C=(7^3 .21 -7^3 .1)/(7^3 . 42-7^3 .2)`
`C=(7^3.(21-1))/(7^3.(42-2))`
`C=(7^3 . 20 )/(7^3 .40)`
`C=(7^3 .20)/(7^3 .2 .20)`
`C=1/2`
Bài `2`
`(2x+1).(x^2-1/4)=0`
`=>`\(\left[ \begin{array}{l}2x+1=0\\x^2 -\dfrac{1}{4}=0\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}2x=0+1\\x^2=0+\dfrac{1}{4}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}2x=1\\x^2=\dfrac{1}{4}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=1:2\\x^2=(±\dfrac{1}{2})^2\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=\dfrac{1}{2}\\x=±\dfrac{1}{2}\end{array} \right.\)
Đáp án:
Bài `1: 1/2`
Bài `2:` \(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{array} \right.\)
Giải thích các bước giải:
Bài `1:`
`C=(7^4 . 3 – 7^3 ) / ( 7^4 . 6 – 7^3 . 2 ) `
`= ( 7^3 . ( 7 . 3 – 1 )) / ( 7^3 . ( 7 . 6 – 2))`
`= ( 7^3 . 20 ) / (7^3 . 40 )`
`= 20 / 40 = 1/2`
Bài `2:`
`c) ( 2x + 1 ) ( x^2 – 1/4 ) = 0`
`=>` \(\left[ \begin{array}{l}2x+1=0\\x^2-\dfrac{1}{4}=0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}2x=-1\\x^2=\dfrac{1}{4}\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-\dfrac{1}{2}\\x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{array} \right.\)