Question

与9a²-16b²相等的式子是

1. A.
   (-4b+3a)(-4b-3a)
2. B.
   (-3a+4b)(-3a-4b)
3. C.
   (4b+3a)(4b-3a)
4. D.
   (3a+2b)(3a-2b)

Answer 1

B
∵(-3a+4b)(-3a-4b)＝(-3a)²-(4b)²＝9a²-16b²．