Please help with explanation

C

Step-by-step explanation:

use the formula = a² + 2ab + b²

(9x)² - 2 * 9x * 7xy + (7xy)²

81x² + 49x²y²- 126x²y

c) 81x² + 49x²y² - 126x²y

Step-by-step explanation:

when you square something you are multiplying it by itself

(9x - 7xy)² = (9x - 7xy) (9x - 7xy)

this requires the FOIL method:

F = first = (9x)(9x) = 81x²

O = outer = (9x)(-7xy) = -63x²y

I = inner = (-7xy)(9x) = -63x²y

L = last = (-7xy)(-7xy) = 49x²y²

the two middle terms can be combined because they are 'like'

-63x²y + -63x²y = -126x²y

81x² - 126x²y + 49x²y²

the order is normally changed to be put in decreasing exponent order so 49x²y² is put before -126x²y

i think the answer is b)

step-by-step explanation:

1gm = 1000mg so 0.1gm = 1000mg

first, convert the weight to kg

160lb * 1kg/2.2lb = 72.7kg

next, the dose

72.7kg * 100mg/kg = 7270mg