ex2) a) (x+4)²=x²+2x×4+4²=x²+8x+16.
b) (a-5)²=a²-2a×5+5²=a²-10a+25.
c) (2x+3)²=(2x)²+2×2x×3+3²=4x²+12x+9.
d) (3x-1)²=(3x)²-2×3x×1+1²=9x²-6x+1.
e) (2x-5)×(2x+5)=(2x)²-5²=4x²-25.
f) (√2+1)²=2+2√2+1=3+2√2.
g) (√3-2)²=3-4√3+4=7-4√3.
h) (√7-√5)×(√7+√5)=7-5=2.
ex3. a) 3x²-5x=x×(3x-5)
b) x³+3x²+x+3=x×(x²+1)+3(x²+1)=(x+3)×(x²+1)
c) x²-14x+49=(x-7)²
d) 4x²+12x+9= (2x+3)²
e) 25x²-81y²=(5x-9y)×(5x+9y).
