Question

solve using substitution
5x+3y=-34 -7x+y=58

Answer 1

id rather use elimination

Answer 2

yea elimination is simpler

Answer 3

whatever works best for you

Answer 4

but isnt that against the rules? it say we have to use subs

Answer 5

either way you use, you will end up with the same answer........right?

Answer 6

5x +3y =-34
-7(-3)x +y(-3) = 58(-3)
---------------------
x(5+21) = 58(-3) -34

x = (58(-3) -34)/(5 + 21)

Answer 7

yep, same answer as long as you do it right :)

Answer 8

when you math it out; x = -8 i believe

Answer 9

use that in either equation to determine the value of y

Answer 10

does y=2

Answer 11

ax + by = t ; (-c)
cx + dy = z ; (a)


-cax -cby = -tc
cax +ady = za
---------------
y(ad - cb) = za - tc

y = (za-tc) / (ad - cb)
^^^
this part is known as a determinant
of a matrix i think

Answer 12

5(-8) +3y =-34

3y = -34 -5(-8)

y = (-34 -5(-8))/3 = 2 yes

Answer 13

Thanks !!!! :)

Answer 14

youre welcome :)