Question

Tìm x:  6 . ( 2x - 7)² + 14 = 50

Answer 1

6(2x-7)²+14=50

6.(2x-7)²=50-14

6(2x-7)²=36

(2x-7)²=6

=> \(\left[{}\begin{matrix}2x-7=6\\2x-7=-6\end{matrix}\right.\left[{}\begin{matrix}2x=13\\2x=1\end{matrix}\right.\left[{}\begin{matrix}x=\dfrac{13}{2}\\x=\dfrac{1}{2}\end{matrix}\right.\)

Answer 2

`6.(2x-7)^2+14=50`

`6.(2x-7)^2=50-14=36`

`(2x-7)^2=36:6=6`

`(2x-7)^2=(\sqrt{6})^2` hoặc `(2x-7)^2=(-\sqrt{6})^2`

`@TH1:2x-7=\sqrt{6}`

       `=>2x=\sqrt{6}+7`

      `=>x=[\sqrt{6}+7]/2`

`@TH2:2x-7=-\sqrt{6}`

     `=>2x=-\sqrt{6}+7`

     `=>x=[-\sqrt{6}+7]/2`

Vậy `x in {[+-\sqrt{6}+7]/2}`

 

Answer 3

6 . (2x - 7)² + 14 = 50

6 . (2x - 7)²         = 50 - 14

6 . (2x - 7)²         = 36

6 . (2x - 7)²        = 36

     (2x - 7)²        = 36 : 6

     (2x - 7)²        = 6

<=> 2x - 7 = 6   <=> 2x = 13 <=> x = 13/2

<=> 2x - 7 = - 6  <=> 2x = 1  <=> x = 1/2

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