=-a( 1-2a+a? )
=-a( 1-a)?
2.9(x+2y)? -25(x-2y)?
=[ 3(x+2y) ]? -[5(x-2y) ]?
=[3(x+2y)+5(x-2y)][3(x+2y)-5(x-2y)]
=(8x-4y)(-2x+ 16y)
=-8(2x-y)(x-8y)
3.x? +x+_ 1/4__=( x+ 1/2)?
4.(7a-8b)? -4x?
=(7a-8b)? -(2x)?
=(7a-8b+2x)(7a-8b-2x)
5.9(a-b)? + 12(a-b)+4
=[3(a-b)]? +2×3(a-b)×2+2?
=[3(a-b)+2]?
=(3a-3b+2)?