Question

Bài 3: Phân tích các đa thức sau thành nhân tử:

a) 36-12x+x².

b) 4x²+12x+9.

c) -25x⁶-y⁸+10x³y⁴.

d) \(\dfrac{1}{4}\)x²-5xy+25y².

Bài 4: Tính nhanh:

a) 75²-25².

b) 53²-47².

c) 31,8²-2.31,8.21,8+21,8².

d) 58,2²+2.58,2.41,8+41,8².

Answer 1

bai 3

a) 36-12x+x²

= x²-12x+36

=(x-6)²

b) 4x²+12x+9

=(2x+3)²

c) -25x⁶-y⁸+10x³y⁴

=-(25x⁶+y⁸-10x³y⁴)

=-(5x³)²+(y⁴)²-10x³y⁴

=-(5x³)²-2.5x³y⁴+(y⁴)

=-(5x³-y⁴)²

d) \(\dfrac{1}{4}\) x²-5xy+25y²

=(\(\dfrac{1}{2}\) x-5y)²

Answer 2

Bài3:

Bạn =kia làm r nhé

Bài4:

\(a,75^2-25^2\\ =\left(75-25\right)\left(75+25\right)\\ =50.100=5000\\ b,53^2-47^2\\ =\left(53-47\right)\left(53+47\right)\\ =6.100=600\\ c,31,8^2-2.31,8.21,8+21,8^2\\ =\left(31,8-21,8\right)^2\\ =10^2=100\\ d,58,2+2.58,2.41,8+41,8^2\\ =\left(58,2+41,8\right)^2\\ =100^2=1000\)