化简并求值(1)(a+2)²-2(a+3)(a-2)+(a-3)² 其中a=-3/4(2)已知丨a+1/2丨+(b-3)²=0,求式子{(2a+b)²+(2a+b)(b-2a)-6b}÷2b的值.
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![化简并求值(1)(a+2)²-2(a+3)(a-2)+(a-3)² 其中a=-3/4(2)已知丨a+1/2丨+(b-3)²=0,求式子{(2a+b)²+(2a+b)(b-2a)-6b}÷2b的值.](/uploads/image/z/5526827-35-7.jpg?t=%E5%8C%96%E7%AE%80%E5%B9%B6%E6%B1%82%E5%80%BC%281%29%28a%2B2%29%26%23178%3B-2%28a%2B3%29%28a-2%29%2B%28a-3%29%26%23178%3B+%E5%85%B6%E4%B8%ADa%EF%BC%9D-3%2F4%EF%BC%882%EF%BC%89%E5%B7%B2%E7%9F%A5%E4%B8%A8a%2B1%2F2%E4%B8%A8%2B%28b-3%29%26%23178%3B%EF%BC%9D0%2C%E6%B1%82%E5%BC%8F%E5%AD%90%7B%282a%2Bb%EF%BC%89%26%23178%3B%2B%282a%2Bb%29%28b-2a%29-6b%7D%C3%B72b%E7%9A%84%E5%80%BC.)
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化简并求值(1)(a+2)²-2(a+3)(a-2)+(a-3)² 其中a=-3/4(2)已知丨a+1/2丨+(b-3)²=0,求式子{(2a+b)²+(2a+b)(b-2a)-6b}÷2b的值.
化简并求值
(1)(a+2)²-2(a+3)(a-2)+(a-3)² 其中a=-3/4
(2)已知丨a+1/2丨+(b-3)²=0,求式子{(2a+b)²+(2a+b)(b-2a)-6b}÷2b的值.
化简并求值(1)(a+2)²-2(a+3)(a-2)+(a-3)² 其中a=-3/4(2)已知丨a+1/2丨+(b-3)²=0,求式子{(2a+b)²+(2a+b)(b-2a)-6b}÷2b的值.
(1)
(a+2)² -2(a+3)(a-2)+(a-3)²
=a² +4a+4 -2(a² +a-6)+a²-6a+9
=a² +4a+4 -2a² -2a+12+a²-6a+9
=a² +a²-2a²+4a -2a-6a+9+4 +12
=-4a+25
=-4*(-0.75)+25
=3+25
=28
(2)
∵|a+ 1/2|+(b+3)2=0,
∴a+ 1/2=0,b-3=0,
∴a=- 1/2,b=3.
[(2a+b)2+(2a+b)(b-2a)-6b]÷2b,
=(4a2+b2+4ab+b2-4a2-6b)÷2b,
=b+2a-3,
当a=- 1/2,b=3时,原式=b+2a-3=3+2×(- 1/2)-3=-1.
(1):-4a+25,值为28
(2):绝对值与二次幂都大于等于0,因为它们加起来是0,所以分别等于0
所以a+1/2=0 b-3=0
所以a=-1/2 b=3
化简式子:原式=2a-2,代入求值:-3