Question

Solve the system using elimination. –10x – 3y = –18 –7x – 8y = 11

Answer 1

ANSWER

x=3, y=-4

EXPLANATION

The given system is :

First equation:

$- 10x - 3y = - 18$

Second equation:

$- 7x - 8y = 11$

Let us multiply the first equation by 7 to get,

Third equation;

$- 70x - 21y = - 126$

Let us multiply the second equation too by 10 to get,

Fourth equation:

$- 70x - 80y = 110$

Subtract the fourth equation from the third equation:

$- 21y + 80y = - 126 - 110$

$59y = -236$

Divide both sides by 59.

$y = - 4$

Put y=-4 into the second equation and solve for x.

$- 7x - 8( - 4) = 11$

$- 7x + 32 = 11$

$- 7x = 11 - 32$

$- 7x = - 21$

$x = 3$

The solution is x=3, y=-4

Answer 2

Answer:

x = 3 and y = -4

Step-by-step explanation:

It is given that,

-10x – 3y = –18      ----(1)

–7x – 8y = 11    -------(2)

Solve equation using elimination

-10x – 3y = –18      ----(1)

10x + 3y = 18

Multiply by 7

70x + 21y = 126    ----(3)

–7x – 8y = 11    -------(2)

-70x - 80y = 110   ---(4)

(3) +(4)

21y - 80y = 126 + 110

-59y = 236

y = 236/(-59) = -4

-10x – 3y = –18      ----(1)

-10x - (3 * -4) = -18

-10x + 12 = -18

-10x = -30

x = 30/10 = 3

Therefore x = 3 and y = -4