Respuesta :

2.8a^2=55
a^2=55/2.8
a= square root of 55/2.8

Answer:

a = 2.62 or - 2.62 (2 d.p.)

Step-by-step explanation:

5a² - 2.2 a² = 85 - 30

2.8 a² = 55

a² = 55/2.8

a = +- sqroot(55/8)

a= 2.6220221204 or - 2.6220221204

a = 2.62 or - 2.62 (2 d.p.)