Respuesta :

konrad509
[tex]2(5a+1)=2(a+1)\\ 10a+2=2a+2\\ 8a=0\\ a=0\\\\ 2\cdot(0+1)=2\cdot 1=2[/tex]

It's 2.
dalendrk
In a rectangle diagonals is equal (|AC| = |BD|), therefore

2(5a + 1) = 2(a + 1)    |divide both sides by 2

5a + 1 = a + 1  |subtract 1 from both sides

5a = a    |subtract "a" from both sides

4a = 0    |divide both sides by 4

a = 0

subtitute to 2(a + 1)

|AC| = |BD| = 2(0 + 1) = 2(1) = 2