Answer:
x²+6x+9
x²+3x+3x+9
x(x+3)+3(x+3)
=(x+3)(x+3)
Step-by-step explanation:
Co interior angles' sum is 180°
Distributive property
Explanation:
You are distributing the 3 to the parenthesis to get 12x+21 =43
you can round 279 to 280