2.1) a) (3a+p)(3a−p)+
p2=9
a^2−3ap+3ap-
p2+
p2=9
a^2;
б) (a+11)^2−20a=
a^2+22a+121−20a=
a^2+2a+
121;
в) 25
a^2−
(c−5a)(c+5a)=25
a^2−
c^2−5ca+5ac+25
a^2=50
a^2−
c^2;
г) 4
x^2−
(x−3y)^2=4
x^2−
x^2+6xy−9
y^2=
3x^2+6xy−9y^2;
2) а) (a+2b)(a−2b)−
(a−b)^2=
a^2-2ab+2ba−4
b^2−
a^2+2ab−
b^2=−2ab+4ba−5
b^2=
2ab−5b^2;
б) (y+x)^2−
(y−x)^2=
y^2+2yx+
x^2−
y^2+2yx−
x^2=4xy;
в) (a−2b)^2+
(a+2b)(a−2b)=a^2−4ab+4b^2+a^2-2ab+2ba−4b^2=2a^2−4ab;
г) (a−5x)^2+
(a+5x)^2=
a^2−10ax+25
x^2+
a^2+10ax+25
x^2=2
a^2+50
x^2;
д) (b−1)(b+1)−(a+1)(a−1)=
b^2+b−b−1−
a^2+a−a+1=
b^2−
a^2;
е) (3a−2)(3a+2)+(a+8)(a−8)=9a^2+6a−6a−4+a^2-8a+8a−64=10a^2−68.
3. На фотографии;
4.a) (1−5x)(1+5x)−(3x−1)^2=1+5x−5x−25x^2−9x^2+6x−1=5x+x−34x^2=6x−34x^2;
б) (a+2b)(2b−a)+(a+3b)=2ab-a^2+4b^2−2ba+a+3b=−a^2+4b^2+3b+a;
