问题 解答题
计算:
(1)(3
ax
-4
by
)(3
ax
+4
by
)

(2)
3
(2+
6
-
3
)

(3)(
2
-
3
+
5
)(
2
+
3
-
5
)

(4)(
2
-1)(
2+1
)2
答案

(1)(3

ax
-4
by
)(3
ax
+4
by
)=(3
ax
2-(4
by
2=9ax-16by;

(2)

3
(2+
6
-
3
)=2
3
+3
2
-3;

(3)(

2
-
3
+
5
)(
2
+
3
-
5
)=(
2
2-(
3
-
5
2=2-3-5+2
15
=-6+2
15

(4)(

2
-1)(
2+1
)2=(
2
-1)×3=3
2
-
3.

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