Question

2x + y = 11
y = 3x - 9
how do i do this using substitution

Answer 1

Answer:

Given that

2x+y=11

y=3x-9

Step-by-step explanation:

2x+y=11 ... ... ...(1)

y=3x-9 ... ... ...(2)

From (2) equation we use y=3x-9 in equation (1)

2x+3x-9=11

5x-9=11

5x=20

x=4

now we use x=4 in equation (2)

y=3.4-9

y=12-9

y=3

the answer of this equations is(x,y)=(4,3)

Answer 2

$\huge{ \underline{{ \mathbf{Given \: : }}}}$

• 2x + y = 11
• y = 3x - 9

$\huge{ \underline{ \bf{To \: find \: : }}}$

• x
• y

$\huge{ \underline{ \underline{ \mathrm{Solution \: : - }}}}$

Let the equation be

• 2x + y = 11 ...............(i)
• 3x - y = 9 ................(ii)

Now, on adding equation (ii) from (i); we get;

$\tt2x + \cancel{y} = 11 \\ \tt3x - \cancel{y} = 09 \\ - - - - - - - \\ \tt 5x =20 \\ \tt \: x = \cancel \frac{20}{ 5} \\ \tt \: x = 4$

Now, on putting x = 4 on equation (i); we get;

$\tt \to2x + y = 11$

$\tt \to2( 4) + y = 11$

$\tt \to 8 + y = 11$

$\tt \to \: y = 11- 8$

$\tt \to \: y =3$

Therefore,

X = 4 and Y = 3