Question

Bài 1: Thực hiện các phép tính:

a) -7x\(^2\)(3x - 4y)           b) (x - 3)(5x - 4)

c) (2x - 1)\(^2\)           d) (x + 3)(x - 3)

Answer 1

Bài 1:

a)

-7x\(^2\)(3x - 4y)

= -7x\(^2\).3x + 7x\(^2\).4y

= -21x\(^3\) + 28x\(^2\)y

b)

(x - 3)(5x - 4)

= x.5x - x.4 - 3.5x + 3.4

= 5x\(^2\) - 4x - 15x + 12

= 5x\(^2\) - 19x + 12

c)

(2x - 1)2\(^2\)

= 4x\(^2\) - 4x + 1

d)

(x + 3)(x - 3)

= x\(^2\) - 3\(^2\)

= x\(^2\) - 9

Answer 2

1,

\(a,=-21x^3+28x^2y\)

\(b,=5x^2-4x-15x+12\)

= \(5x^2-19x+12\)

\(c,=4x^2-4x+1\)

\(d,=x^2-3x+3x-9=x^2-9\)