If you expand out the brackets you get this,
(4+5i)(a+2i) = 4a + (5a)i + 8i - 10
The -10 comes from 5i * 2i.
Squaring i becomes -1.
Let's group the real stuff together,
and imaginary separately,
(4a - 10) + (5a + 8)i
For this to be purely imaginary,
the real part needs to be zero.
Therefore 4a - 10 = 0
Solve for a.
3b+6
If you make both equations equal each other, you can then solve the system of equations.
<span>10.6325909767 rounded to the nearest 10th is 10.633</span>
That means that the first rectangle and the first triangle ave athe same perimiter
so therefor
perimiter=sides added up
rectangle has 4 sides bu 2 is given so double it since the other side is same legnth
rec=x+x+4
multiply 2
2x+2x+8=4x+8=perimiter
this is equal to perimiter of triangle which is
x+9+x+5+x=3x+14
therefor
4x+8=3x+14
subtract 3x from both sides
x+8=14
subtract 8 from both sides
x=6
first one x=6
second rectangle and second triangle
s+7 and 3s
2 sides
2s+14+6s=p
8s+14=p
traignel=2s+12+2s+12+2s+12=6s+36=p
they are equal so
8s+14=6s+36
subtract 6s from both sides
2s+14=36
subtract 14 from both sides
2s=22
divide both sideds by 2
s=11
the values are
pair one:
x=6
pair 2:
s=11