Pre Calc, how to you solve an equation if it says a≠0?

[tintin1234]

it says "use the inverses found in Problems 29-38 to solve each system of equations"(not sure what it means by that)
pg742,#47)
2x+y= -3
ax+ay=-a
a≠0 <----a≠0 was already in the book next to the equation
the book says the answer is x=-2,y=1
-what i have so far-
[2 1] [-3] --> (2 x a)-(a x 1) = 1a
[a a]=[-a]
[a -1]
A^-1= 1/det(A) x [-a 2]

[a -1] [1 -1/a]
A^-1= 1/1a x [-a 2] = [-1 2/a] <---inverse

[x] [1 -1/a] [-3]
[y] = [-1 2/a] [-a]


50) bx+3y= 14
bx+2y=10
b≠0 <------b≠0 was already in the book next to the equation

My math book is called "Precalculus seventh edition Sullivan", its a dark green/blue color(just in case you might have it). on pg 742 it says "show that each matrix has no inverse"

 

[Mark44]

it says "use the inverses found in Problems 29-38 to solve each system of equations"(not sure what it means by that)
pg742,#47)
2x+y= -3
ax+ay=-a
a≠0 <----a≠0 was already in the book next to the equation
the book says the answer is x=-2,y=1
-what i have so far-
[2 1] [-3] --> (2 x a)-(a x 1) = 1a
[a a]=[-a]
[a -1]
A^-1= 1/det(A) x [-a 2]

[a -1] [1 -1/a]
A^-1= 1/1a x [-a 2] = [-1 2/a] <---inverse

[x] [1 -1/a] [-3]
[y] = [-1 2/a] [-a]

Everything looks fine, so far. What do you get for x and y when you do the matrix multiplication on the right?

50) bx+3y= 14
bx+2y=10
b≠0 <------b≠0 was already in the book next to the equation

My math book is called "Precalculus seventh edition Sullivan", its a dark green/blue color(just in case you might have it). on pg 742 it says "show that each matrix has no inverse"

Do the same thing you did in the previous problem to find the solution for this problem.