Algebra
posted by Kelly on .
I need help with two math problems.
1. A triangle has vertices (1, 4), (1, 1), and (3, 1). The triangle is dilated by a scale factor of 2, then translated 5 units up, and then rotated 90 degrees counterclockwise about the origin. What are the vertices of the image of the triangle?
2. Use matrices to solve the system.
2x+3y=4
5x+8y=11
I appreciate the help!

1.
The transformations are:
e(O,2) : dilation about origin of 2 units
t(0,5) : translation 5 units up
r(y,x) : rotation counterclockwise 90°
So
(x,y)> (2x,2y) > (2x, 2y+5) > (2y+5, 2x)
So combining it all:
(x,y) > (2y+5, 2x)
2.
Using Cramer's rule:
Δ=8*23*5=1
x=(4*811*3)/Δ=1
y=(2*115*4)/Δ=2
Check:
2(1)+3*2=4
5(1)+8*2=11
ok. 
I'm still confused on the first one. Thank you. I appreciate it.

I need help