Question

Solve the simultaneous equations (SOLVE FOR X AND Y)
5x + y = 21
x - 3y = 9

EXPLAIN IN DETAIL

Answer 1

solve by elimination method you will get the same answer

Answer 2

The solution is $(\frac{9}{2},\frac{-3}{2})$

Step-by-step explanation:

Given simultaneous equations are $5x+y=21\hfill (1)$ and

$x-3y=9\hfill (2)$

To solve the given simultaneous equation :

That is to find the solution

• Solving the given equations by elimination method :
• Multiply the equation (2) into 5 we get

$5x-15y=45\hfill (3)$

Now subtracting the equations (1) and (3) we get

$5x+y=21$

$5x-15y=45$

(-)__(+)__(-)______

      $16y=-24$

•    $y=\frac{-24}{16}$

Therefore $y=-\frac{3}{2}$

Substitute the value of y in equation (1) we get

• $5x-\frac{3}{2}=21$
• $5x=21+\frac{3}{2}$
• $5x=\frac{21(2)+3}{2}$
• $5x=\frac{45}{2}$
• $x=\frac{45}{2\times 5}$
• $=\frac{9}{2}$

Therefore $x=\frac{9}{2}$

Therefore the values of x and y are $\frac{9}{2}$ and $\frac{-3}{2}$ respectively

The solution is $(\frac{9}{2},\frac{-3}{2})$