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人気のある代数 >

A=-5x^2+78x+21

解

A = - 5 x^{2} + 78 x + 21

解

x = - \frac{- 39 + - 5 A + 1626}{5}, x = \frac{- 5 A + 1626 + 39}{5}

解答ステップ

A = - 5 x^{2} + 78 x + 21

辺を交換する

- 5 x^{2} + 78 x + 21 = A

A

を左側に移動します

- 5 x^{2} + 78 x + 21 - A = 0

解くとthe二次式

x_{1, 2} = \frac{- 78 \pm 7 8 ^{2} - 4 ( - 5 ) ( 21 - A )}{2 ( - 5 )}

簡素化

7 8^{2} - 4 (- 5) (21 - A) : 2 - 5 A + 1626

x_{1, 2} = \frac{- 78 \pm 2 - 5 A + 1626}{2 ( - 5 )}

解を分離する

x_{1} = \frac{- 78 + 2 - 5 A + 1626}{2 ( - 5 )}, x_{2} = \frac{- 78 - 2 - 5 A + 1626}{2 ( - 5 )}

x = \frac{- 78 + 2 - 5 A + 1626}{2 ( - 5 )} : - \frac{- 39 + - 5 A + 1626}{5}

x = \frac{- 78 - 2 - 5 A + 1626}{2 ( - 5 )} : \frac{- 5 A + 1626 + 39}{5}

二次equationの解:

x = - \frac{- 39 + - 5 A + 1626}{5}, x = \frac{- 5 A + 1626 + 39}{5}

グラフ

人気の例

x^{2} + 99 = 16 x + 10

solvefor x,y=x^2-6x

so l v e f or x, y = x^{2} - 6 x

solvefor x,f(x-2)=x^2+9x+5

so l v e f or x, f (x - 2) = x^{2} + 9 x + 5

- t^{2} + 12 t = 32

5 R^{2} - 10 R = 0