Question

9(x+5)^2-4(x-7)^2 giúp em vs ak.dạ hồi nãy làm đề bị sai

Answer 1

\(9\left(x+5\right)=9x+45\)

Answer 2

=9x+45

Answer 3

= 9x + 45x

Answer 4

\(9\left(x+5\right)^2-4\left(x-7\right)^2\\ =9\left(x^2+10x+25\right)-4\left(x^2-14x+49\right)\\ =9x^2+90x+225-4x^2+56x-196\\ =9x^2-4x^2+90x+56x+225-196\\ =5x^2+146x+29\)

Answer 5

= 9.(x^2 + 10x + 25) - 4.(x^2 - 14x + 49)

= 9x^2 + 90x + 225 - 4x^2 + 56x - 196

= 5x^2 + 146x + 29