(5x-9)^2 please help

Question

I'm kinda confused is it 25x^2+81 or no.

Answer 1

(a + b)² = (a + b)(a + b) = a² + 2ab + b²

 

a = 5x

b = -9

 

(5x - 9)² = (5x)² + 2(5x)(-9) + (-9)² = 25x² - 90x + 81

 

So the answer to your question is NO.

Answer 2

The expanded form is 25x^2-90x+81.

 

(5x-9)*(5x-9)

25x^2-45x-45x+81

25x^2-90x+81