Question

x+y=7 and x-y=1 then find xy​

Answer 1

Answer:

12 is your answer.

Step-by-step explanation:

given that x + y = 7

                  x - y = 1

   on adding the given equations, we get

              x + y + x - y = 7 + 1

                  2x = 8

                    x = 4

when x = 4 we can find the value of y by

substituting x in any of those equations

     x + y = 7

     4 + y = 7

     y = 7 - 4

     y = 3

     xy = (3)(4)

     xy = 12

              Hope it helps you.

Please mark it as the brainliest answer.

Answer 2

Answer:

Step-by-step explanation:

ANSWER:-

Methods to be used:-

• Substitution Method
• Elimination Method

By substitution Method:-

x-y=7

x = 7+y_______________(1)

In Equation number 2,

x-y=1

Now, we can place the value of x here as:-

(7+y)-y=1

Hence it is not possible by Substitution Method.

By Elimination Method:-

(x+y)+(x-y)= 7+1

2x = 8

x = 8/2 = 3.

Now placing the values of x in Any equation, (say 1),

3+y = 7

y = 7-3

y = 4.

Now, xy

xy = 3*4 = 12.

So, 12 is the answer.

• Elimination Method is used when we need to remove one number to find the another number.
• However, we can find the value of eliminated number by placing the value of found number in any of the given equation.
• In Substitution Method, we find the value of one constant with respect to the another constant.
• Here also we can find the value of any constant by placing value of found constant at any one equation( As 2 variables provides 2 equations).