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受欢迎的代数 >

7f^2=f+1

解答

7 f^{2} = f + 1

解答

f = \frac{1 + 29}{14}, f = \frac{1 - 29}{14}

+1

十进制

f = 0.45608 \dots, f = - 0.31322 \dots

求解步骤

7 f^{2} = f + 1

将

1

para o lado esquerdo

7 f^{2} - 1 = f

将

f

para o lado esquerdo

7 f^{2} - 1 - f = 0

改写成标准形式

a x^{2} + b x + c = 0

7 f^{2} - f - 1 = 0

使用求根公式求解

f_{1, 2} = \frac{- ( - 1 ) \pm ( - 1 ) ^{2} - 4 \cdot 7 ( - 1 )}{2 \cdot 7}

(- 1)^{2} - 4 \cdot 7 (- 1) = 29

f_{1, 2} = \frac{- ( - 1 ) \pm 29}{2 \cdot 7}

将解分隔开

f_{1} = \frac{- ( - 1 ) + 29}{2 \cdot 7}, f_{2} = \frac{- ( - 1 ) - 29}{2 \cdot 7}

f = \frac{- ( - 1 ) + 29}{2 \cdot 7} : \frac{1 + 29}{14}

f = \frac{- ( - 1 ) - 29}{2 \cdot 7} : \frac{1 - 29}{14}

二次方程组的解是:

f = \frac{1 + 29}{14}, f = \frac{1 - 29}{14}

作图

流行的例子

x^2+(x-2)^2=130

x^{2} + (x - 2)^{2} = 130

m^{2} - 2 m + 10 = 0

solvefor x,(x-6)^2+(y+4)^2+z^2=25

so l v e f or x, (x - 6)^{2} + (y + 4)^{2} + z^{2} = 25

x^{2} = 7 x - 6

- x^{2} - 10 x = 34