gtnn:
A = 3 | 2x+5| + 12.6
=> A = 3.|2x+5| + 72
De A nho nhat thi |2x+5| = 0
=> A = 3.0+72 = 72
Vay gtnn cua A la 72
gtln:
A = 3.|2x+5| + 12.6
=> A = 3.|2x+5|+ 72
De A lon nhat thi |2x+5| > 0
=> A = 3.z + 72 ( voi z la 1 so bat ki lon hon 0 )
=> A > 75
Vay: gtln cua A la lon hon 75