化简3x^2-{5x-(2分之1x-3)}+2x^2}

3x^2-{5x-(1/2x-3)}+2x^2}
=3x^2-{5x-1/2x+3+2x^2}
=3x^2-2x^2-9/2x-3
=3/2(2x^2-3x-2)
=3/2(x-2)(2x-1)
5a+{3b+{6c-2a-(a-c)}}-{9a-(7a+c}
=5a+{3b+6c-2a-a+c}-{9a-7a-c}
=5a+{3b+7c-3a}-2a+c
=2a+3b+7c-2a+c
=3b+8c