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受欢迎的代数 >

(d+1)(d-5)=2d^2-7

解答

(d + 1) (d - 5) = 2 d^{2} - 7

解答

d = - 2 - 6, d = 6 - 2

+1

十进制

d = - 4.44948 \dots, d = 0.44948 \dots

求解步骤

(d + 1) (d - 5) = 2 d^{2} - 7

展开

(d + 1) (d - 5) : d^{2} - 4 d - 5

d^{2} - 4 d - 5 = 2 d^{2} - 7

将

7

para o lado esquerdo

d^{2} - 4 d + 2 = 2 d^{2}

将

2 d^{2}

para o lado esquerdo

- d^{2} - 4 d + 2 = 0

使用求根公式求解

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

(- 4)^{2} - 4 (- 1) \cdot 2 = 26

d_{1, 2} = \frac{- ( - 4 ) \pm 2 6}{2 ( - 1 )}

将解分隔开

d_{1} = \frac{- ( - 4 ) + 2 6}{2 ( - 1 )}, d_{2} = \frac{- ( - 4 ) - 2 6}{2 ( - 1 )}

d = \frac{- ( - 4 ) + 2 6}{2 ( - 1 )} : - 2 - 6

d = \frac{- ( - 4 ) - 2 6}{2 ( - 1 )} : 6 - 2

二次方程组的解是:

d = - 2 - 6, d = 6 - 2

作图

流行的例子

4 = 3 t^{2} - t

(x+5)(x-1)-7(x+1)=-3x-3

(x + 5) (x - 1) - 7 (x + 1) = - 3 x - 3

p^{2} + 3 p + 2 = 0

solvefor x,x(x+5)=-6

so l v e f or x, x (x + 5) = - 6

x^{2} - 2 x = \frac{5}{2}