Question

Thực hiện phép tính:
a) 5x+3.(x²-x-1)
b) (5-x).(5+x)-(2x-1)²
c) (x⁴+2x³+10x-25):(x²+5)

Answer 1

a. 5x + 3(x² - x - 1)

= 5x + 3x² - 3x - 3

= 3x² + 5x - 3x - 3

= 3x² + 2x - 3

b. (5 - x)(5 + x) - (2x - 1)²

25 - x² - (4x² - 4x + 1)

= 25 - x² - 4x² + 4x - 1

= 25 - 1 - x² - 4x² + 4x 

= 24 - 5x² + 4x

Answer 2

a) \(5x+3\left(x^2-x-1\right)=5x+3x^2-3x-3=3x^2+2x-3\)

b) \(\left(5-x\right)\left(5+x\right)-\left(2x-1\right)^2=25-x^2-4x^2+4x-1=-5x^2+4x+24\)

 

Answer 3

\(a) 5x+3(x^2-x-1)=5x+3x^2-3x-3\)

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

\(b)(5-x)(5+x)-(2x-1)^2=25-x^2-4x^2+4x-1\)

\(=-5x^2+4x-24\)