Question

Упростите выражение
((a+3b)2/4(a-3b)-4a): 3a+9b/24a-16•a2-9b2/5a2-18ab-3b2 и найдите его значение при a=-2/3, b=7/3

Answer 1

1)(a+3b)²/[4(a-3b)]-4a=(a²+6ab+9b²-16a²+48ab)/[4(a-3b)=
=(-15a²+54ab+9b²)/[4(a-3b)]=-3(5a²-18ab-3b²)/[4(a-3b)]
2)-3(5a²-18ab-3b²)/[4(a-3b)]* 8(3a-2)/[3(a+3b)] * (a-3b)(a+3b)/(5a²-18ab-3b²)=
=-2(3a-2)=4-6a
a=-2/3,b=7/3    4-6*(-2/3)=4+4=8