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please give me the method of solving the following : the sum of the ages of dad & son is 45. 5yrs ago the product of their age was 34. what is the age of dad & son?

2007-01-04 21:58:47 · 13 answers · asked by vinu 1 in Science & Mathematics Other - Science

13 answers

let Dad's age be 'd' and son's age be 's'.
so from the given data d+s=45
condition 2: 5 yrs ago age of son =s-5
5 yrs ago age of dad=d-5
given (s-5)*(d-5)=34
by trial error we get the values as 2 and 17,1 and 34
so son is 1yrs and dad is 34 yrs
Finally the Present age of son is 6 and dad is 39 so their sum is 45.

2007-01-04 22:11:14 · answer #1 · answered by Anonymous · 1 0

let dad's age be d and son's age be s

sum of their ages is 45

s + d = 45
d = 45 - s...(1)

5 yrs ago product of their ages was 34

(s-5)x(d-5) = 34...(2)

Substituting (1) in (2)

(s-5)x(40-s) = 34
(s-5)(s-40)+34=0
s^2 + 234 - 45s = 0

solve this quadratic equation using determinant method

D = 45^2 - 4x234x1 = 1089
s = 45 +or- sqrt(D)
-------------------
2

s = (45+33)/2 = 39 yrs old
But this makes the dad 6 yrs old which is impossible hence we go for the second solution
s =(45-33)/2 = 6 yrs old

therefore son is 6 yrs old and dad 39 yrs old

2007-01-04 22:40:46 · answer #2 · answered by Anonymous · 0 0

Let the son's and the dad's present ages be 's' and 'd'

According to the conditions stated above,
s + d = 45 .......(i)
(s-5)(d-5) = 34 .......(ii)

Substituting d = (45-s) in (ii), we get

(s-5)(45-s-5) = 34

s^2 - 45 s +234 = 0

The solution for this eqn is s = 39 or 6.

Answer :
Dad's present age = 39
Son's present age = 6

2007-01-04 22:21:00 · answer #3 · answered by Poornima G 2 · 0 0

trial and error or simultanously

let d be the age of dad and s be the age of son
d+s=45 ---(1)
(d-5)(s-5)=34 ---(2)

from (1), d=45-s ---(3)

subst (3) into (2)
(45-s-5)(s-5)=34
(40-s)(s-5)=34
40s-200-s^2+5s=34
45s-234-s^2=0
s^2-45s+234=0
(s-6)(s-39)=0

hence s=6 or 39
subst both ans to get d age

d=39 or 6

thus dad is 39 years old while son is 6 years old(:

2007-01-04 22:27:32 · answer #4 · answered by pigley 4 · 0 0

representation: x=dad and y=son
PRESENT: x+y=45....... 5 YRS. AGO: xy=34
formula: x+y = 5+xy
solution: find numbers to enable to get the product of x and y...
34,1 or 17,2
multiply both: 34*1= 34
add 5 years to both factors: 34+5+1+5=45
FINAL ANSWER: 5 YRS. Ago dad was 34 yrs. old and son was 1 yr. old.....NOW: dad is 39 yrs. old and son is 6 yrs.old

2007-01-04 22:19:42 · answer #5 · answered by -arika- 2 · 0 0

let the age of father and son be x and y
x+y=45 ..........eqn 1
5 yrs ago
(x-5)(y-5)=34 .......eqn 2
sub eqn 2 in eqn 1
(40-y)(y-5)=34
y*y-45y+234=0
solving this y=6,then sub in eqn 1,x=39
another method product of two ages is 34 which have only two options 17,2 &34,1.From this we can find easily.But first is the universal method while the second is just a short cut method.

2007-01-04 22:29:01 · answer #6 · answered by baskysaravana6 3 · 0 0

D+A = 35
(D-5)(A-5) = 34

DA -5A -5D = 34
DA = 34+ 5*35 = 209
D = 35-A
(35-A)A=209
35A - A^2 = 209
A^2 -35A +209 = 0

this is a quadratic for the age of the son or dad

2007-01-04 22:15:47 · answer #7 · answered by beanie_boy_007 3 · 0 0

d + s = 45.5
(d-5) x (s-5) =34

So you have two equations and two unknowns.

Rearranging the first equation gives s=45.5-d
Substituting in the second equation gives....

(d-5) x (45.5-d-5) = 34

(d-5) x (40.5-d) = 34

-202.5 -d^2+5d-40.5d = 34

Solve this quadratic equation and choose the positive solution for d. When you know d you can find s by putting the value of d in any of the equations.

use the formula -b plus or minus the square root of blah blah blah. to solve the quadratic equation.

You do the rest and I'll get back to my job!

2007-01-04 22:16:10 · answer #8 · answered by Anonymous · 0 0

33 dad $ 12 son

2007-01-04 22:33:06 · answer #9 · answered by vishu k 1 · 0 0

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2016-12-12 04:17:23 · answer #10 · answered by ? 4 · 0 0

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