Question

54:19 To eliminate the terms and solve for y in the fewest steps, by which constants should the equations be multiplied by before adding the equations together? First equation: 9x + 3y = -18 Second equation: 8x + 7y = 10 The first equation should be multiplied by 3 and the second equation by 7. The first equation should be multiplied by -3 and the second equation by -7. The first equation should be multiplied by - 7 and the second equation by 3 . The first equation should be multiplied by -7 and the second equation by -3.

Answer 1

Answer:

The first equation should be multiplied by - 7 and the second equation by 3

Step-by-step explanation:

Given

$9x + 3y = -18$ -- (1)

$8x + 7y = 10$ -- (2)

Required

How to eliminate y

In (1), the coefficient of y = 3

In (2), the coefficient of y = 7

Multiply the first equation by -7

$-7(9x + 3y = -18)$

$-63x -21y = 126$ --- (3)

Multiply the second by 3

$3(8x + 7y = 10)$

$24x + 21y = 30$ -- (4)

Add the results together:

$-63x -21y = 126$

$24x + 21y = 30$

$-------------------------$

$-63x + 24x -21y +21y = 126+30$

$-63x + 24x = 126+30$

See that y is eliminated