Question

replace the third equation by the sum of itself and -1 times the second equation x-2y-7z=17,-6x+4y+5z=-9,8x+7y=z=-4

Answer 1

Answer:

$14x+3y-6z=5$

Step-by-step explanation:

$x-2y-7z=17$ --- 1

$-6x+4y+5z=-9$ --- 2

$8x+7y-z=-4$ ---3

-1 times the second equation = $-1(-6x+4y+5z=-9)$

                                                 = $6x-4y-5z=9$  --4

Now we are given that replace the third equation by the sum of itself and -1 times the second equation

So, New third equation = $8x+7y-z+6x-4y-5z=-4+9$

                                       = $14x+3y-6z=5$

Hence the new third equation is $14x+3y-6z=5$