Question

if x+y=5 then x-y =10​

Answer 1

Answer:

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Explanation:

x+y=5 [1]

x−y=10 [2]

To solve for x and y, you should rearrange one of the equations for one of the variables x or y. Choose equation [1] to rearrange for y, because it is easy to do so.

y=5−x [3]

Now, substitute this expression into equation [2]:

x(5−x)=6

Now use this equation to solve for x. Firstly expand the parentheses:

5x−x2=6

Rearrange the terms so that they are all on one side of the equation:

x2−5x+6=0

What you have here is a quadratic equation. There are many ways to solve a quadratic equation but I will choose the easiest method for this problem.

Factorise the quadratic expression on the left-hand side of the equation by using the product-sum method (or by decomposition):

(x−2)(x−3)=0

The null factor law gives x=2 or x=3 as the solution.

Now, substitute x=2 or x=3 into equation [3] to get the value of y:

when x=2, then  y=5−2=3  

when x=3, then y=5−3=2

Therefore, there are two solutions to these simultaneous equations, which are: (2,3) and (3,2) ■

Answer 2

Answer:

x + y = 5 ……..(1)

x - y = 10 ……….(2)

Now subtracting (2) from (1) we get,

x - y -(x +y ) = 10 -5

X - y - x - y = 5.

-2y = 5

Y = -5/2……..(3)

now put this value in equation (2) we get,

X - ( -5/2) = 10

X + 5/2

X = 10- 5/2

X = 15/2.