The product of two 2- Digit numbers is 1998. If the product of their units digit is 28 and that of tens digit is 15, find the numbers. Answer with out imaginary letter or number.
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Step-by-step explanation:
let the two digits number be x and y where,
x=10a+b
y=10c+d
xy =1998
ac=16
bd=28
xy =(10a+b)(10c+d)
1998=(10a+b)(10c+d)
1998=100ac+10ad+10bc+bd
1998=100x15+10ad+10bc+2
1998-1528=10(ad+bc)
470=10(ad+bc)
47=ad+bc
47=15d/c+bc
47=15d+bc2/c
47c=15d+bc2
bc2=47c+15d=0
c=-q+-√Q2-4pr/2p
=-(-47)+-√(47)2-4xbx15xd/2b
=47+-√2209-60xbd /2b
=47+-√2209-60x28/2b
=47+-√2209-1608/2b
=47+-√529/2b=47+-23/2b
c=70/2b,24/2b
c=35/b,12/b
bc=35 or 12
by substituting
47=ad+35
ad=12
a*28/b=12
47=ad+12
ad=35
a/b=35/28
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