AMC10 2005 A

AMC10 2005 A · Q3

AMC10 2005 A · Q3. It mainly tests Linear equations.

The equations $2x + 7 = 3$ and $bx -10 = -2$ have the same solution $x$. What is the value of $b$?

方程 $2x + 7 = 3$ 和 $bx -10 = -2$ 有相同的解 $x$。求 $b$ 的值。

(A) -8 -8

(B) -4 -4

(D) 4 4

(E) 8 8

Answer

Correct choice: (B)

正确答案：（B）

Solution

Since $2x + 7 = 3$ we have $x = -2$. Hence $-2 = b(-2) -10$, so $2b = -8$, and $b = -4$.

由 $2x + 7 = 3$ 得 $x = -2$。因此 $-2 = b(-2) -10$，所以 $2b = -8$，$b = -4$。

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