SOLUTION: The sum of two numbers is 77 and the product of the two numbers is 1440. I found 30 x 48 = 1440 but their sum is 78 Where did I go wrong?

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Question 580366: The sum of two numbers is 77 and the product of the two numbers is 1440.
I found 30 x 48 = 1440 but their sum is 78
Where did I go wrong?

Found 2 solutions by jim_thompson5910, josmiceli:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
First, list out the factors of :
1,2,3,4,5,6,8,9,10,12,15,16,18,20,24,30,32,36,40,45,48,60,72,80,90,96,120,144,160,180,240,288,360,480,720,1440
-1,-2,-3,-4,-5,-6,-8,-9,-10,-12,-15,-16,-18,-20,-24,-30,-32,-36,-40,-45,-48,-60,-72,-80,-90,-96,-120,-144,-160,-180,-240,-288,-360,-480,-720,-1440


Note: list the negative of each factor. This will allow us to find all possible combinations.


These factors pair up and multiply to .
1*1440 = 1440
2*720 = 1440
3*480 = 1440
4*360 = 1440
5*288 = 1440
6*240 = 1440
8*180 = 1440
9*160 = 1440
10*144 = 1440
12*120 = 1440
15*96 = 1440
16*90 = 1440
18*80 = 1440
20*72 = 1440
24*60 = 1440
30*48 = 1440
32*45 = 1440
36*40 = 1440
(-1)*(-1440) = 1440
(-2)*(-720) = 1440
(-3)*(-480) = 1440
(-4)*(-360) = 1440
(-5)*(-288) = 1440
(-6)*(-240) = 1440
(-8)*(-180) = 1440
(-9)*(-160) = 1440
(-10)*(-144) = 1440
(-12)*(-120) = 1440
(-15)*(-96) = 1440
(-16)*(-90) = 1440
(-18)*(-80) = 1440
(-20)*(-72) = 1440
(-24)*(-60) = 1440
(-30)*(-48) = 1440
(-32)*(-45) = 1440
(-36)*(-40) = 1440

Now let's add up each pair of factors to see if one pair adds to :


First NumberSecond NumberSum
114401+1440=1441
27202+720=722
34803+480=483
43604+360=364
52885+288=293
62406+240=246
81808+180=188
91609+160=169
1014410+144=154
1212012+120=132
159615+96=111
169016+90=106
188018+80=98
207220+72=92
246024+60=84
304830+48=78
324532+45=77
364036+40=76
-1-1440-1+(-1440)=-1441
-2-720-2+(-720)=-722
-3-480-3+(-480)=-483
-4-360-4+(-360)=-364
-5-288-5+(-288)=-293
-6-240-6+(-240)=-246
-8-180-8+(-180)=-188
-9-160-9+(-160)=-169
-10-144-10+(-144)=-154
-12-120-12+(-120)=-132
-15-96-15+(-96)=-111
-16-90-16+(-90)=-106
-18-80-18+(-80)=-98
-20-72-20+(-72)=-92
-24-60-24+(-60)=-84
-30-48-30+(-48)=-78
-32-45-32+(-45)=-77
-36-40-36+(-40)=-76


From the list above, we see that the row highlighted in red is our answer.


So


32 + 45 = 77

and

32*45 = 1440


which means that the two numbers are 32 and 45.

Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
Let the numbers be and


---------------

and



Use quadratic formula










and





The numbers are 32 and 45
check:


OK

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