12-(4x-18)=(36+5x)+(28-6x)
12-4x+18=36+5x+28-6x
30-4x=-x+64
-4x+x=64-30
-3x=34
x=-34/3
x=-11 1/3
3Sin( - 3П/2) = - 3Sin3П/2 = - 3 * (- 1) = 3
81c² - d² + 9c + d = (81c² - d²) + (9c + d) = (9c - d)(9c + d) + (9c + d) =
= (9c + d)(9c - d + 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
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