在同一幅图上画出 y=1+a−2x−ay = 1 + \frac{a - 2}{x - a} 和 y=−1ax+2ay = -\frac{1}{a}x + \frac{2}{a} 的图像,其中 aa 是一个正常数且 1<a<21 < a < 2,并清晰标出所有渐近线和与坐标轴的交点。

  1. (i)

    利用图像,用 aa 表示,解不等式 1+a−2x−a>−1ax+2a1 + \frac{a - 2}{x - a} > -\frac{1}{a}x + \frac{2}{a}。

  2. (ii)

    由此,解不等式 1+ax−2x1−ax>−1ax+2a1 + \frac{ax - 2x}{1 - ax} > -\frac{1}{ax} + \frac{2}{a}。

先不看答案,让 AI 诊断你卡在哪里?

它不会直接告诉你答案,而是问你卡在哪一步看看 AI 是怎么陪你一步步弄懂这道题的

完整解法

10(i)

1. Identify the points of intersection of the curve and the line from their axial intercepts.

From the prior sketch, the axial intercepts of the curve y=1+a−2x−ay = 1 + \frac{a - 2}{x - a} are found at x=0  ⟹  y=1+a−2−a=2ax=0 \implies y = 1 + \frac{a-2}{-a} = \frac{2}{a} and y=0  ⟹  a−2x−a=−1  ⟹  x=2y=0 \implies \frac{a-2}{x-a} = -1 \implies x=2.
Similarly, the axial intercepts of the line y=−1ax+2ay = -\frac{1}{a}x + \frac{2}{a} are at x=0  ⟹  y=2ax=0 \implies y = \frac{2}{a} and y=0  ⟹  x=2y=0 \implies x=2.
Thus, the curve and the line intersect exactly at (0,2a)(0, \frac{2}{a}) and (2,0)(2, 0).

2. Determine the range of $x$ where the curve is above the line.

The inequality 1+a−2x−a>−1ax+2a1 + \frac{a - 2}{x - a} > -\frac{1}{a}x + \frac{2}{a} means we require the curve to be strictly above the line.
Observing the relative positions of the graphs and considering the vertical asymptote is at x=ax = a (where 1<a<21 < a < 2), the curve is above the line between the yy-intercept and the vertical asymptote, and also to the right of the xx-intercept.
Therefore, the solution is 0<x<a0 < x < a or x>2x > 2.

答案

0<x<a or x>20 < x < a \text{ or } x > 2

10(ii)

1. Determine the solution for part (i) to use in the current part

To answer the target, we first establish the solution to part (i).
Find the xx-coordinates of the intersections of the curve and the line:
1+a−2x−a=−1ax+2a1 + \frac{a-2}{x-a} = -\frac{1}{a}x + \frac{2}{a}
x−a+a−2x−a=2−xa\frac{x-a+a-2}{x-a} = \frac{2-x}{a}
x−2x−a=2−xa\frac{x-2}{x-a} = \frac{2-x}{a}
(x−2)[1x−a+1a]=0(x-2) \left[ \frac{1}{x-a} + \frac{1}{a} \right] = 0
(x−2)[a+x−aa(x−a)]=0(x-2) \left[ \frac{a+x-a}{a(x-a)} \right] = 0
x(x−2)a(x−a)=0  ⟹  x=0 or x=2\frac{x(x-2)}{a(x-a)} = 0 \implies x = 0 \text{ or } x = 2
Using the properties of the graphs, the curve lies above the line for the intervals:
0<x<aorx>20 < x < a \quad \text{or} \quad x > 2

2. Manipulate the target inequality to match the form in part (i)

Rearrange the inequality given in (ii) to reveal its relation to (i).
Factorize xx in the numerator of the rational expression and then divide both the numerator and denominator by xx:
1+x(a−2)x(1x−a)>−1a(1x)+2a1 + \frac{x(a - 2)}{x\left(\frac{1}{x} - a\right)} > -\frac{1}{a}\left(\frac{1}{x}\right) + \frac{2}{a}
1+a−21x−a>−1a(1x)+2a1 + \frac{a - 2}{\frac{1}{x} - a} > -\frac{1}{a}\left(\frac{1}{x}\right) + \frac{2}{a}
This is identical to the inequality from part (i), but with xx replaced by 1x\frac{1}{x}.

3. Apply the substitution to the solution from part (i)

Substitute 1x\frac{1}{x} into the solution bounds found in (i):
0<1x<aor1x>20 < \frac{1}{x} < a \quad \text{or} \quad \frac{1}{x} > 2

4. Solve the reciprocal inequalities to find the final bounds for $x$

Solve these inequalities for xx.
For 0<1x<a0 < \frac{1}{x} < a:
Since a>0a > 0 and 1x>0\frac{1}{x} > 0, we know x>0x > 0. Taking the reciprocal reverses the inequality sign:
x>1ax > \frac{1}{a}

For 1x>2\frac{1}{x} > 2:
Similarly, 1x\frac{1}{x} is positive, meaning x>0x > 0. Taking the reciprocal gives:
x<12x < \frac{1}{2}
Thus, 0<x<120 < x < \frac{1}{2}.

Combining these, the final solution is:
0<x<12orx>1a0 < x < \frac{1}{2} \quad \text{or} \quad x > \frac{1}{a}

答案

0<x<12 or x>1a0 < x < \frac{1}{2} \text{ or } x > \frac{1}{a}

AI 分析,可能出错

用 AI 批改,圈出写错的那一步,并自动将你的薄弱点存入错题本,形成你的错因库。

同一知识点的其他题

  1. 1曲线 C1C_1 的方程为 p2x2−y2=p2p^2x^2 - y^2 = p^2,其中 p>1p > 1。 画出 C1C_1 的草图,用 pp 表示出其与坐标轴的所有交点坐标、所有驻点坐标以及所有渐近线方程。 C1C_1 经过单一变换得到 C2C_2。…
  2. 2在同一幅图中,画出 y=∣2x+3∣y = |2x + 3| 和 y=−2x2−8x−3y = -2x^2 - 8x - 3 的图像。 (你不需要标出任何轴交点和驻点。) 精确求解不等式 ∣2x+3∣>−2x2−8x−3|2x + 3| > -2x^2 - 8x - 3。
  3. 3在同一个图上,画出满足下列条件的 y=∣2x−p∣y = |2x - p| 和 y=qxy = qx 的图像草图,标出轴交点。 * pp 和 qq 是常数,p>1p > 1 且 q>0q > 0,以及 * 图像仅有一个交点。 写出 qq 的最小值。 解不…
  4. 4在同一坐标系中,画出 y=5−1x−1y=5-\dfrac{1}{x-1} 和 y=1(x−5)2y=\dfrac{1}{(x-5)^2} 的图像草图。 解不等式 5−1x−1<1(x−5)25-\dfrac{1}{x-1}<\dfrac{1}{(x-5)^2}。
  5. 5曲线 CC 的方程为 y=x2+kx+4x+1y = \frac{x^2 + kx + 4}{x + 1},其中 kk 为常数。 若 CC 有两个不同的驻点,求 kk 的取值范围。 在接下来的问题中,使用 k=4k = 4。 画出 CC 的图像,清晰地…