I'm sure there's an easier way of solving it than the way I did, but I'm not sure what it could be. Never dealt with a problem like this before.
Anyway, I just plugged in and tested. Chose random values for a, b, c, and d, which follow the rule 0 < a < b < c < d:
a = 1
b = 2
c = 3
d = 4


Simplify into standard form:



Use the quadratic formula to solve:

For functions in the form of

. So in this case:
a = 1
b = -4
c = 2
Plug them in:

Solve for 'x':




So the answer would be A.
Answer:
Step-by-step explanation:
look this solution
Answer:
x=0
Step-by-step explanation:
For the
writer, <span><span>there are 20
1.
</span>1
+ 39 = 40</span>
<span><span>
2.
</span>2
+ 38 = 40</span>
<span><span>3.
</span>3
+ 37 = 40</span>
<span><span>4.
</span>4
+ 36 = 40</span>
<span><span>
5.
</span>5
+ 35 = 40</span>
<span><span>
6.
</span>6
+ 34 = 40</span>
<span><span>7.
</span>7
+ 33 = 40</span>
<span><span>8.
</span>8
+ 32 = 40</span>
<span><span>
9.
</span>9
+ 31 = 40</span>
<span><span>10.
</span>10
+ 30 = 40</span>
<span><span>
11.
</span>11
+ 29 = 40</span>
<span><span>
12.
</span>12
+ 28 = 40</span>
<span><span>13.
</span>13
+ 27 = 40</span>
<span><span>
14.
</span>14
+ 26 = 40</span>
<span><span>
15.
</span>15
+ 25 = 40</span>
<span><span>
16.
</span>16
+ 24 = 40</span>
<span><span>
17.
</span>17
+ 23 = 40</span>
<span><span>
18.
</span>18
+ 22 = 40</span>
<span><span>
19.
</span>19
+ 21 = 40</span>
<span><span>
20.
</span>20
+ 20 = 40</span>