Answer:
1. Use FOIL method
(4-2x) (4+2x)
= 4(4) + 4(2x) + (-2x) (4) + (-2x) (2x)
= 16 + 8x + (-8x) - 4x^2
= 16 + 8x change the + sign to negative sign - 8x because we have different sign - 4x^2 therefore
= 16 + 8x - 8x - 4x^2
= 16 +0 - 4x^2
= 16 - 4x^2
2. (3xy-abc) (3xy+abc)
= (3xy) (3xy) + (3xy) (abc) + (-abc) (3xy) + (-abc) (abc)
= 9x^2y^2 + 3abcxy + (-3abcxy) + (-a^2b^2c^2)
= 9x^2y^2 + 3abcxy change sign -3abcxy -a^2b^2c^2
= 9x^2y^2 + 3abcxy - 3abcxy - a^2b^2c^2
= 9x^2y^2 + 0 - a^2b^2c^2
= 9x^2y^2 - a^2b^2c^2
3. (x^2 +4y^2) (x^2 - 4y^2)
= (x^2) (x^2) + (x^2) (-4y^2) + (4y^2) (x^2) + (4y^2) (-4y^2)
= x^4 + (-4x^2y^2) + 4x^2y^2 + (-16y^4)
= x^4 change sign -4x^2y^2 +4x^2y^2 -16y^4
= x^4 -4x^2y^2 +4x^2y^2 -16y^4
= x^4 + 0 -16y^4
= x^4 - 16y^4
4. .[2+(x-1)][2-(x-1)]
=( 2 + x-1) (2 - x + 1) why naging negative? Dahil yan sa parehas silang sign na negative pag parehas always positive sign.
= (2 + x -1) ( 2 - x+1) minus or plus the coefficient
= (x + 1) ( -x + 3)
= x(-x) + x(3) + 1(-x) + 1(3)
= -x^2 + 3x - x + 3
= -x^2 + 2x + 3
Sana makatulong. Pagbutihan nyo ang pag aaral nyo
