A=(y+3)^2
=(y×y)+(y×3)+(3×3)+(3×y)
=y^2+3y+9+3y
=y^2+6y+9
B=(1+t)^2
=(1×1)+(1×t)+(t×t)+(t×1)
=1+t+t^2+t
=t^2+2t+1
C=(7-y)^2
=(7×7)-(7×y)+(y×y)-(y×7)
=49-7y+y^2-7y
=y^2-14y+49
D=(3x-10)^2
=(3x×3x)-(3x×10)+(10×10)-(10×3x)
=9x^2-30x+100-30x
=9x^2-60x+100
E=(7-2y)(7+2y)
=(7×7)+(7×2y)-(2y×7)-(2y×2y)
=49+14y-14y-4y^2
=-4y^2+49
F=(7a+4)^2
=(7a×7a)+(7a×4)+(4×4)+(4×7a)
=49a^2+28a+16+28a
=49a^2+56a+16
