观察单项式:2a;﹣4aˆ2;8aˆ3;﹣16aˆ4……根据规律,第n个式子是1+3=4=2² 1+3+5=9=3² 1+3+5+7=16=4² 1+3+5+7+9=25=5²那么1+3+5+7+9+…+(2n-1)=
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![观察单项式:2a;﹣4aˆ2;8aˆ3;﹣16aˆ4……根据规律,第n个式子是1+3=4=2² 1+3+5=9=3² 1+3+5+7=16=4² 1+3+5+7+9=25=5²那么1+3+5+7+9+…+(2n-1)=](/uploads/image/z/3910845-21-5.jpg?t=%E8%A7%82%E5%AF%9F%E5%8D%95%E9%A1%B9%E5%BC%8F%EF%BC%9A2a%EF%BC%9B%EF%B9%A34a%26%23710%3B2%EF%BC%9B8a%26%23710%3B3%EF%BC%9B%EF%B9%A316a%26%23710%3B4%E2%80%A6%E2%80%A6%E6%A0%B9%E6%8D%AE%E8%A7%84%E5%BE%8B%2C%E7%AC%ACn%E4%B8%AA%E5%BC%8F%E5%AD%90%E6%98%AF1%EF%BC%8B3%3D4%3D2%26%23178%3B+1%EF%BC%8B3%EF%BC%8B5%3D9%3D3%26%23178%3B+1%EF%BC%8B3%EF%BC%8B5%EF%BC%8B7%3D16%3D4%26%23178%3B+1%EF%BC%8B3%EF%BC%8B5%EF%BC%8B7%EF%BC%8B9%3D25%3D5%26%23178%3B%E9%82%A3%E4%B9%881%EF%BC%8B3%EF%BC%8B5%EF%BC%8B7%EF%BC%8B9%EF%BC%8B%E2%80%A6%EF%BC%8B%282n%EF%BC%8D1%29%3D)
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观察单项式:2a;﹣4aˆ2;8aˆ3;﹣16aˆ4……根据规律,第n个式子是1+3=4=2² 1+3+5=9=3² 1+3+5+7=16=4² 1+3+5+7+9=25=5²那么1+3+5+7+9+…+(2n-1)=
观察单项式:2a;﹣4aˆ2;8aˆ3;﹣16aˆ4……根据规律,第n个式子是
1+3=4=2² 1+3+5=9=3² 1+3+5+7=16=4² 1+3+5+7+9=25=5²
那么1+3+5+7+9+…+(2n-1)=
观察单项式:2a;﹣4aˆ2;8aˆ3;﹣16aˆ4……根据规律,第n个式子是1+3=4=2² 1+3+5=9=3² 1+3+5+7=16=4² 1+3+5+7+9=25=5²那么1+3+5+7+9+…+(2n-1)=
(-1)^(n+1)*(2a)^n
n^2
n²
逢奇数时 4na的n次方,偶数时-4na的n次方