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Math algebra. 50 points!!!!!!

Math algebra. 50 points!!!!!!-example-1
User Jose Rocha
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2 Answers

5 votes

Given equations,

→ 3x - y = 6

→ 6x + y = 21

Forming the equation for y,

→ 6x + y = 21

→ y = -6x + 21

Now the value of x will be,

→ 3x - y = 6

→ 3x + 6x - 21 = 6

→ 9x = 6 + 21

→ x = 27/9

→ [ x = 3 ]

Then the value of y will be,

→ y = -6x + 21

→ y = -6(3) + 21

→ y = -18 + 21

→ [ y = 3 ]

Now the value of x and y is,

→ x = 3, y = 3

Hence, the value of both is 3.

User Slouei
by
8.5k points
3 votes

Answer:

x = 3, y = 3

Explanation:

Given system of equations:


\begin{cases}3x-y=6\\6x+y=21 \end{cases}

Add the two equations to eliminate y:


\begin{array}{crcccl}& 3x & - & y & = & \phantom{.}6\\+ & (6x & + & y & = & 21)\\\cline{2-6}& 9x &&&=&27\\\cline{2-6}\end{aligned}

Solve for x:


\implies 9x=27


\implies x=\frac{27}9}


\implies x=3

Substitute the found value of x into one of the equations and solve for y:


\implies 6x+y=21


\implies 6(3)+y=21


\implies 18+y=21


\implies y=21-18


\implies y=3

Therefore, the solution to the given system of equations is:

  • x = 3
  • y = 3
User Beata
by
8.5k points

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