Question 4.4. Solve, using the substitution method.

y + 2x = 7
14 – 4x = 2y

(Points : 1)
The solution is (1, 5)
The solution is (21, 0)
There are an infinite number of solutions.
There is no solution.

Question

Question 4.4. Solve, using the substitution method.

y + 2x = 7
14 – 4x = 2y

(Points : 1)
       The solution is (1, 5)
       The solution is (21, 0)
       There are an infinite number of solutions.
       There is no solution.

vishweshshrimali5 · Answer

What would be the value of y in terms of x from first equation ?

vishweshshrimali5 · Answer

We have:

$$\large{y + 2x = 7}$$

$$\large{y = 7 - 2x}$$

Any doubt ?

anonymous · Answer

no doubt @vishweshshrimali5

vishweshshrimali5 · Answer

Great!! Now in second equation:

$$\large{14 - 4x = 2y}$$

Now, I put the value of y I obtained from eq. 1 in eq.2

vishweshshrimali5 · Answer

That is:

$$\large{14 - 4x = 2(7 - 2x)}$$

vishweshshrimali5 · Answer

What if I simplify the RHS?

That is:

$$\large{2(7-2x) = 2 * 7 - 2*2x = 14 - 4x}$$

Any doubt ?

anonymous · Answer

no doubt again Lol 
@vishweshshrimali5

vishweshshrimali5 · Answer

:)

So, regardless of what x is, LHS and RHS are equal. 

Thus: every x will satisfy the equations. So, infinite solutions