Can't figure out these math problems....Help very much appreciated

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1

<p>Can't figure out these couple problems. Help appreciated.</p>

<ol>
<li>In the xy-plane, line L contains the points (j,k) and (2j,2k), where j and k are both positive. Which of the following is an equation of line L in terms of j and k?
A y=j/k(x)
B y=k/j(x)
C y=k/j(x) + k
D y=j/k(x) + j
E y=2x+j+k</li>
</ol>

<p>And also,</p>

<ol>
<li>How many positive four-digit even integers have a 5 in the thousands place, a 2 in the tens place, and at least one of the digits equal to 6?</li>
</ol>

2

<p>y=m(x-a)+b</p>

<p>m=k/j</p>

<p>y=k/j(x) </p>

<p>Its a line, so it will go through the origin.</p>

<p>**</p>

3

<p>5000
0020
0006</p>

<p>Need to have those:
5X2Y: X or Y needs to be 6
16, 26, etc: 9
61, 62, etc: 8 (overlap at 66)</p>

<p>Thus 17.</p>

4

<p>explain the second answer in a better more clear way please. i dont understand it . :)</p>

5

<p>

So the number looks like
5<em>2</em>
Also, it is even and at least one number is 6.</p>

<ol>
<li><p>If the last digit is 6, the hundreds digit can be any number from 0-9
5026, 5126, 5226, 5326, … , 5926 => 10 numbers</p></li>
<li><p>If the Hundreds digit is 6, the units digit can be any even number from 0-9
5620, 5622, 5624, 5626, 5628 => 5 numbers</p></li>
</ol>

<p>But 5626 has been included in both lists, so the total is 10+5-1 = 14</p>

6

<p>this answer makes more sense! i would assumer answer is 14 ?</p>

7

<p>

</p>

<p>Explain the ‘Its a line so it will go through the origin’ part please.</p>

8

<p>^Well calculate the slope and then use one of the points and the point (0,x) to find the y-intercept, x will be zero, so it will go through the origin. </p>

<p>When he said ‘Its a line so it will go through the origin’, that really makes no sense, because not all lines go though the origin.</p>