Given A-B = 1, A2 + B2 = 25, then the value of a + B is () A. 7B. -7C. ±7D. ±9

Given A-B = 1, A2 + B2 = 25, then the value of a + B is () A. 7B. -7C. ±7D. ±9

∵ A-B = 1, ∵ (a-b) 2 = 12, ∵ A2 + b2-2ab = 1, then 25-2ab = 1, so AB = 12, then (a + b) 2 = A2 + B2 + 2Ab = 25 + 2 × 12 = 49, then a + B = ± 7, so C

Factorization: 1 + 4A ^ - 4A=

Original form
=4a²-4a+1
=（2a）²-2a×a+1
=（2a-1）²

How to factorize a4-4a2 + 140?

a4-4a2+140
It can't be factorized
Upstairs is a4-4a2-140

When factoring - 4a2 + B2, the correct result is ()
A. （2a+b）（2a-b）B. 4（a+b）（a-b）C. -（2a+b）（2a-b）D. -4（a+b）（a-b）

-4a2 + B2 - (4a2-b2) = - (2a + b) (2a-b)