a−3)
2
=a
+3
−2∗3∗a=a
+9−6a
(2x+y)^2=(2x)^2+y^2+2*2x*y=4x^2+y^2+4xy(2x+y)
=(2x)
+y
+2∗2x∗y=4x
+4xy
(5b-4x)(5b+4x)=(5b)^2-(4x)^2=25b^2-16x^2(5b−4x)(5b+4x)=(5b)
−(4x)
=25b
−16x
a−3)
2
=a
2
+3
2
−2∗3∗a=a
2
+9−6a
(2x+y)^2=(2x)^2+y^2+2*2x*y=4x^2+y^2+4xy(2x+y)
2
=(2x)
2
+y
2
+2∗2x∗y=4x
2
+y
2
+4xy
(5b-4x)(5b+4x)=(5b)^2-(4x)^2=25b^2-16x^2(5b−4x)(5b+4x)=(5b)
2
−(4x)
2
=25b
2
−16x
2