If the ratio of x + y to x − y is 4 1 1 , then the ratio of y to x can be written as b a , where a and b are coprime positive integers. Find a + b .
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
this makes me feel dumb even though im the smartest in my grade
nice solution ! I love you
We can write:
x + y : x − y = 1 1 : 4
x − y x + y = 4 1 1
4 ( x + y ) = 1 1 ( x − y )
4 x + 4 y = 1 1 x − 1 1 y
4 y + 1 1 y = 1 1 x − 4 x
1 5 y = 7 x
y = 1 5 7 x
x y = 1 5 7
So, a = 7 and b = 1 5
Thus the answer is: a + b = 7 + 1 5 = 2 2
We here use the method of componendo and dividendo according to which, if y x = b a ⟹ x − y x + y = a − b a + b . Given that, x − y x + y = 4 1 1
It is said that, x y = b a
⟹ y x = a b
⟹ x − y x + y = b − a b + a
⟹ 4 1 1 = b − a b + a
⟹ 4 b + 4 a = 1 1 b − 1 1 a ⟹ 7 b = 1 5 a ⟹ b a = 1 5 7
So, now we have b a = 1 5 7 where a and b are coprime, a=7 and b=15, so a + b = 7 + 1 5 = 2 2
Nice solution !
Perfect!
Same method!!! :D
4 ( x + y ) = 1 1 ( x − y ) 4 x + 4 y = 1 1 x − 1 1 y 1 5 y = 7 x x y = 1 5 7 a + b = 7 + 1 5 = 2 2
simple and good
How it be possible that a=7 &b=15.A should be "7K"&b should be"15K".where 'k' is a constant.
Log in to reply
Yeah , I too thought this way
a and b have to be coprime integers
given that : (x-y) : (x+y) = 11:4
there fore x:y = (11+4 ) : (11-4) ==>x:y = 15 : 7 as given x:y =a : b
we got a=15 and b=7 ==> (a+b)=15+7 = 22 Ans
We can construct the ratio X+Y/X-Y=11/4 . Cross-multiplying gives us ; therefore7X=15Y, . After further division, this gives usY/X=7/15=A/B . Our answer is7+5= .22
x + y = 11 x-y = 4 2x = 15 x = 15/2 Change x by 15/2, the result is 15/2 + y = 11 then y = 7/2 to gain y/x solution: 7/2(under this fraction put a long vinculum) over 15/2 then 7/2 times 2/15 is equals to 7/15. Therefore a + b = 7 + 15 = 22
(x+y)/(x-y)=11/4,
4(x+y)=11(x-y),
15y=7x,
y/x=7/15=a/b,
a+b=7+15= 22
method 1st- applying componendo and dividendo... method 2nd- dividing numetator and denominator of L.H.S. by x.
(x+y)/(x-y) = 11/4 then, (x+y+x-y)/(x+y-x+y) = (11+4)/(11-4) or, 2x/2y=15/7 or x/y=15/7 = b/a so a+b=15+7=22
(x+y)/(x-y)=11/4 Let x/y=p (p+1)/(p-1)=11/4 here after calculaton p=15/7 a/b=15/7 a+b=15+7 =22
(x+y)/(x-y)=11/4 =>4x+4y=11x-11y =>15y=7x =>y/x=7/15 there fore a+b=7+15=22
Escrevendo a razão de acordo com o que informa o problema:
x+y/x-y = 11/4 4x + 4y = 11x - 11y 15y = 7x
Então:
15/7 = a/b a + b = 15 + 7
Logo, a + b = 22.
(x+y)/(x-y)=11/4 (1+k)/(1-k)=11/4 where k=y/x 4+4k=11-11k 15k=7 k=7/15 therefore a/b=15/7 a+b=22
by componendo and dividendo
x+y/x-y=11/4 4x+4y=11x-11y 7x=15y x/y=15/7 y/x=7/15 a+b=22
by solving the equn x+y =11 x-y=4 we get x=15/2 y=7/2 while writing this in the ratio form we get a/b = 7/15 which corresponds a= 7 and b=15.....therefore a+b =22
If x/y=a/b, then x+y/x-y=a+b/a-b. This is called componendo and dividendo. Use that and you'll get the solution.
Cross multiply equation; find x and y ; find y x ; reduce to simplest terms; add; submit.
Given,
x − y x + y = 4 1 1
Since we require x y , we apply dividendo-componendo ,
( x + y ) + ( x − y ) ( x + y ) − ( x − y ) = 1 1 + 4 1 1 − 4
2 x 2 y = 1 5 7
x y = 1 5 7
Hence, a + b = 7 + 1 5 = 2 2
That's the answer!
(x + y ) : ( x - y) = 11/4 ---> 4x + 4y = 11x - 11y ---> 15y = 7x ---> y/x = 7/15. So,a + b = 7 + 15 = 22. Answer : 22
(x + y)/(x - y) = 11/4
4x + 4y =11x -11y
7x = 15y
the addition of both coefficient of the unknowns = 22
x+Y/x-y +1 =11/4 +1: 2x/x-y = 15/4 -(1) x+y/x-y -1 = 11/4 - 1 ; 2y/x-y = 7/4 -(2) divide (1) by (2) we get x/y =15/7 so a+b= 15+ 7 = 22
x+y/x-y=11/4, 2x/2y=15/7, x/y=15/7=b/a, a+b=15+7=22.
Problem Loading...
Note Loading...
Set Loading...
We can construct the ratio x − y x + y = 4 1 1 . Cross-multiplying gives us 4 x + 4 y = 1 1 x − 1 1 y ; therefore, 7 x = 1 5 y . After further division, this gives us x y = 1 5 7 . Our answer is 7 + 1 5 = 2 2 .