Question

como hallar la longitud de las bases de un trapecio de base mayor 6x-3 base menor 2x+5 base media 21cm

Answer 1

Tenemos.

Base mayor = 6x - 3
Base menor = 2x + 5
Base media = 21cm

Formula .

Base media = (Base mayor + Base menor)/2

21 = (6x - 3 + 2x + 5)/2
21 * 2 = 8x + 2
42 = 8x + 2
42 - 2   = 8x
40 = 8x
40/8 = x
5 = x
Bas mayor = 6x - 3 = 6 * 5 - 3 = 30 - 3 = 27cm
Base menor = 2x + 5 = 2 * 5 + 5 = 10 + 5 = 15cm

Respuesta.
La base mayor mide 27cm y la menor 15cm

Answer 2

La base media se halla sumando base mayor mas base menor sobre dos.
 x = 5 :v