4a4 + 20a2 + 25
= (2a2)2 + 2(2a2).5 + 52
= (2a2 + 5)2
sử dụng hằng đẳng thức (a+b)2 nhé!
\(4a^4+20a^2+25=[\left(2a^2\right)^2+2.2a^2.5+5]+20\)
\(=\left(2a^2+5\right)^2+20\)
\(4a^4+20a^2+25=\left(2a\right)^2+2\cdot5\cdot2a+5^2=\left(2a+5\right)^2\)
Giải
4a4 + 20a2 + 25
= ( 2a2 )2 + 2. 2a2 . 5 + 52
= ( 2a2 + 5 ) 2
Study well
Mk nhầm!Phải là:
\(4a^4+20a^2+25=\left(2a^2\right)^2+2\cdot5\cdot2a^2+5^2=\left(2a^2+5\right)^2\)
4a^4+20a^2+25
= (2a2) +2.2a2 . 5 + 52
= ( 2a2 + 5 )2
Vậy ...
