Answer:
55
Step-by-step explanation:
Just add them together. 1+2=3; 3+3=6; 6+4=10; 10+5=15; 15+6=21; 21+7=28; 28+8=36; 36+9=45; 45+10=55.
Answer:
81x² - 81
Step-by-step explanation:
Step 1: Write expression
(9x - 9)(9x + 9)
Step 2: Expand by FOIL
81x² + 81x - 81x - 81
Step 3: Combine like terms
81x² - 81
9 x 9 = 81
81 - 21 = 60
60 / -6
10
B
Because 2 sqrt5 is = to sqrt 20.
4^2=16, 6^2=36
