(x-5)^2-4(x-5)-21=0

解答

(x - 5)^{2} - 4 (x - 5) - 21 = 0

x = 12, x = 2

求解步骤

(x - 5)^{2} - 4 (x - 5) - 21 = 0

展开

(x - 5)^{2} - 4 (x - 5) - 21 : x^{2} - 14 x + 24

x^{2} - 14 x + 24 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 14 ) \pm ( - 14 ) ^{2} - 4 \cdot 1 \cdot 24}{2 \cdot 1}

(- 14)^{2} - 4 \cdot 1 \cdot 24 = 10

x_{1, 2} = \frac{- ( - 14 ) \pm 10}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- ( - 14 ) + 10}{2 \cdot 1}, x_{2} = \frac{- ( - 14 ) - 10}{2 \cdot 1}

x = \frac{- ( - 14 ) + 10}{2 \cdot 1} : 12

x = \frac{- ( - 14 ) - 10}{2 \cdot 1} : 2

二次方程组的解是:

x = 12, x = 2

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

0 = x^{2} - 5 x + 6

lo g_{10} (5)

lo g_{0.5} (1)

\frac{2}{- 10}