How do you solve the following system?: 8x+6y=9,−5x−7y=−2

2 Answers
G_Ozdilek
May 3, 2017

With some arrangement. x=5126 and y=−2926

Explanation:

Expand the first equation with term 5
Expand the second equation with 8.

Now you have:

40x+30y=45
−40x−56y=−16
Now sum these up:
−26y=29

or y=−2926

Now you can find x using the first or second equation:

8x−6⋅2926=9

8x=9+6⋅2926

8x=(11713)+(3⋅2913)

8x=20413

x=204104

or

x=5126

Soumalya Pramanik
May 3, 2017

x=12526, y=−121182

Explanation:

8x+6y=9 ....................(i)
−5x−7y=−2 ....................(ii)

You can solve this system by using Elimination method.

You can eliminate either x or y here.
I will eliminate x.

So multiplying eq.(i) by +5 and eq(ii) by +8, you will get

40x+30y=45 ......................(iii) &
−40x−56y=−16 ........................(iv)

Adding eq (iii) and (iv), you will get

−26y=29

⇒ y=−2926

Substituting y=−2926 in eq(i), you will get

8x+(−2926)⋅6=9

⇒ 8x=9+8713

⇒ 8x=117+8713

⇒ 8x=20413

⇒ x=204104=5126

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