3a+2b=54，2a+3b=56，求 ab 的值？

数学题解答：有两个未知数，需要先分别求出a和b，再来算出ab的值。

可以将两个算式的左边相加，右边也相加。这样就得到一个新的等式：

3a+2b+2a+3b = 54+56

整理后得：5a+5b=110，再整理一下，变成：

5(a+b)=110，可以算出：a+b=22

把3a+2b=54变成：a+2a+2b=54，由a+b=22可以知道：2a+2b=44，所以：

a+44=54，所以a=10。

把2a+3b=56变成：2a+2b+b=56，由a+b=22可知2a+2b=44，所以b+44=56，所以：44+b=56，所以b=12。

最后算出ab=10×12=120。

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