Intercepts of a line

Geometry Level 1

The line : 5 x + 7 y 35 = 0 \ell: 5x+7y-35 = 0 intersects the x-axis at ( a , 0 ) (a,0) and the y-axis at ( 0 , b ) (0,b) . What is the value of a + b a+b ?


The answer is 12.

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10 solutions

Siti Zulhusna
Aug 26, 2013

a=x b=y

To find the 'x' which is 'a',you have to change the 'y' in the equation to 0 because x-axis intersects at (a,0).

5x+7(0) -35 =0

5x - 35 = 0

5x=35

x=35/5

x=7

To find the 'y' which is 'b',you have to change the 'x' in the equation to 0 because y-axis intersects at (0,b).

5(0)+7y - 35 =0

7y - 35 = 0

7y=35

y=35/7

y=5

So, 7+5 = 12

Trevor O'Neil
Aug 27, 2013

1. for the equation 5x+7y-35=0, you need to solve for both x and y in order to be able to find (a,b) to do this, plug the y-value of (a,0) into the equation which will then look like this 5x+7(0)-35=0, and in doing so, you can then solve for value of the x coordinate.

2. the next step is do the same exact thing you did for step 1, except instead of replacing y with a 0, you will replace the x with a 0, in order to solve for the y-coordinate.

3. once you are done with both of steps one and two, plug in the (x,y) coordinates that you have found into what is being represented as the (x,y) coordinates, (a,b), and once that is done, you can plug a and b into the equation a+b, where you will find your answer.

Rakesh Lal
Aug 27, 2013

5x+7y-35=0; =>5x+7y=35; =>(5x+7y)/35=1; =>x/7+y/5=1 therefore x-intercept =7 i.e. a=7; y-intercept=5 i.e. b=5; => a+b=5+7=12

Tarek Saazeb
Aug 25, 2013

According to coordinate geometry, in x axis y=0, and in y axis x=0. By putting x=0 in the equation we get y= 5, and putting y=0 in the equation we get x =7, so the points are (7,0) and (0,5) respectively. Thus a+b = 5+7 = 12

Jomarie Cabuello
Sep 1, 2013

5x + 7y - 35 = 0 can be written as 5x + 7y = 35

To find the values of a and b, we have to consider the conditions required. a can only be found by making y equal to 0 and b by making x equal to 0. Upon solving we can have a = 7 and b = 5.

So the solution to the problem is a + b = 5 + 7 = 12.

12 is the correct answer.

Ritwik Upadhyay
Aug 31, 2013

the line 5x+7y-35=0 should be put to the formula of THE STRAIGHT LINE "ax+by+c=0"(let's assume a&b as two integers.). putting the value a=5 &b=7 we can easily get the value of a+b

Basem Hesham
Aug 27, 2013

when x= 0 >>> y =5 , , , , , when y=0 >>> x=7 ,,,,, then line ℓ will intersects the x- axis at (5,0) & (0,7) then a+b = 5+7 =12 the answer is = 12

Abdul Alim
Aug 27, 2013

Given the line: 5x+7y-35=0 or, 5x/35+7y/35=35/35 or, x/7+y/5=1 which is similar to an ideal straight line x/a+y/b=1 where a=7,b=5 so, a+b=7+5=12

Thomas Kelly
Aug 26, 2013

Plugging in 0's for the x and y values proves effective here. Therefore

5x + 0 - 35 = 0 5x = 35 x = 7

Then

0 + 7y - 35 = 0 7y = 35 y = 5

where y = 0 that is where the x intersect lies on the y axis and where x = 0 that is where the y intersects on the x axis. So a = 7 and b = 5

7 + 5 Answer is 12

x=a,y=b

Anmol Jain - 7 years, 9 months ago
Sanjeevkumar E
Aug 26, 2013

As 5x+7y-35=0. Just substitute the given 2 points separately in the equation x=a,y=b then you will come with, for the first point (a,0)=> 5a+7*0=35=>a=7, Similarly for the next point (0,b)=>b=5. 7+5=12. thats solved. :)

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