SAT Math Level 2 Question

Test Preparation SAT Subject Test Preparation
1

<p>Hello everyone,</p>

<p>I have a question about an exercise. The exercise is the following:</p>

<p>which of the following could represent the equation of the inverse of the graph in the figure?</p>

<p>(A)y=-2x+1</p>

<p>(B)y=2x+1</p>

<p>(C) y=1/2x+1</p>

<p>(D) y=1/2x-1</p>

<p>(E) y=1/2x-1/2</p>

<p>the line in the graph intersects the x axis on the point (-1,0) and the y axis on the point (0,1)</p>

<p>I took the slope=y1-y2/x1-x2 and then y-yo=λ(χ-χο) but i find it incorrect. Where I am doing wrong??</p>

<p>the correct is (E) by the way,</p>

2

<p>Wait, if the line passes through point (-1,0) and (0,1), shouldn’t its equation be y = x?</p>

<p>If so then the inverse of that equation will give the exact same line. :S</p>

<p>But you said the correct answer was (E), so working backwards…</p>

<p>y = 1/2x-1/2
x = 1/2y-1/2
x+1/2 = 1/2y
2x+1 = y</p>

<p>We get y = 2x+1, which means it cannot pass through point (-1, 0).</p>

3

<p>

</p>

<p>Uh…if y=x, we’d have (-1,-1) and (0,0).</p>

4

<p>The question (or your representation of it is flawed).
If the line has x-intercept at (-1,0) and y-intercept at (0,1) then slope of the line is:</p>

<p>m = (0-1)/(-1-0) = 1</p>

<p>Therefore, equation of line is y=x+1</p>

<p>Inverse of y=x+1 is y=x-1</p>

<p>[…]</p>

<p>Now, you say that the answer is y=(x/2)-(1/2)
solving backwards,</p>

<p>=>y = 2*(x+(1/2))
=>y = 2x+1</p>

<p>In which case, the graph of the line must intersect the y axis at (0,1) - which it does already. BUT, it should intersect the x axis at (-1/2,0) and NOT (-1,0).</p>

<p>Are you sure that you read the question accurately?</p>

5

<p>First of all thank you all for your answers.</p>

<p>I wrote the question as it is in the book. The explanation of the answer is kinda fuzzy or I didnt understand it correctly.</p>

<p>I did the same like you guys and I found the same solution again and again.</p>

<p>The explanation of the answer is:</p>

<p>

</p>

6

<p>The answer and the explanation is wrong. Reflection of y = x + 1, about y = x, would have the same gradient i.e. 1, and would be y = x - 1.</p>