Question

Solve by linear combination: 7x-28y=11 14x+42y=1

Answer 1

In this case, we'll have to carry out several steps to find the solution.

Step 01:

Data

7x-28y=11 eq.1

14x+42y=1​ eq.2

x = ?

y = ?

Step 02:

linear combination

7x-28y=11 * (-2)

14x+42y=1​

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7x*(-2)-28*(-2)y=11*(-2)

14x+42y=1​

----------------------------

-14x + 56y = -22

14x + 42y = 1​

----------------------------

+ 98y = - 21

y = -21 / 98 = - 3 /14

y in eq.1

7x - 28y = 11

7x - 28 ( -3/14) = 11

`\begin{gathered} 7x\text{ + }(84)/(14)\text{ = 11 } \\ 7x\text{ + 6 = 11} \end{gathered}`

7x = 11 - 6

x = 5 / 7

The answer is:

x = 5/7

y = -3 /14