Đáp án:
$34)
a)4ab\\
b) 6a^2b\\
35)
a) 10000\\
b) 2500\\
36)
a) 10000\\
b) 1000000$
Giải thích các bước giải:
$34)
a) (a+b)^2-(a-b)^2=a^2+2ab+b^2-(a^2-2ab+b^2)\\
=a^2+2ab+b^2-a^2+2ab-b^2=4ab\\
b) (a+b)^3-(a-b)^3-2b^3\\
=a^3+3a^2b+3ab^2+b^3-(a^3-3a^2b+3ab^2-b^3)-2b^3\\
=a^3+3a^2b+3ab^2+b^3-a^3+3a^2b-3ab^2+b^3-2b^3\\
=(a^3-a^3)+(3a^2b+3a^2b)+(3ab^2-3ab^2)+(b^3+b^3-2b^3)\\
=6a^2b\\
35)
a) 34^2+66^2+68.66\\
=34^2+2.34.66+66^2\\
=(34+66)^2\\
=100^2=10000\\
b) 74^2+24^2-48.74\\
=74^2-2.74.24+24^2\\
=(74-24)^2\\
=50^2\\
=2500\\
36)
a) x^2+4x+4=x^2+2.x.2+2^2=(x+2)^2\\
\Rightarrow (98+2)^2=100^2=10000\\
b) x^3+3x^2+3x+1=(x+1)^3\\
\Rightarrow (99+1)^3=100^3=1000000$