Question

1. Thực hiện phép tính sau :

a) 3x (x² - 3x +5)

b) (3x+2y) (3x-2y)

c) (4x² +4x+1):(2x+1)

2. Tính nhanh : 37^{2 -} 74.7 + 7²

Answer 1

1

a

3x(x^2-3x+5)

= 3x^3- 9 x^2+15x

b

(3x+2y)(3x-2y)

= (3x)^2- (2y)^2

=9 x^2- 4 y^2

c

4x^2+4x+1:(2x+1)

= (2x+1)^2:(2x+1)

= (2x+1)

Answer 2

c 37^{2 -} 74.7 + 7²

=37²-2.37.7+7²

=(37-7)²

=30²

=900

Answer 3

1)

a) \(3x\left(x^2-3x+5\right)\)

\(=3x^3-9x^2+15x\)

b) \(\left(3x+2y\right)\left(3x-2y\right)\)

\(=9x^2-4y^2\)

c) \(\left(4x^2+4x+1\right):\left(2x+1\right)\)

\(=\left(2x+1\right)^2:\left(2x+1\right)\)

\(=2x+1\)

2)

\(37^2-74.7+7^2\)

\(=37^2-2.37.7+7^2\)

\(=\left(37-7\right)^2\)

\(=30^2\)

\(=900\)