Simplifying help please

Question

simplify : (5+m)²+(m-2)(m+2)-2m(m+5) ; (c+3)²-2c(c-2)+(c-4)(c+4). Help please...

Answer 1

 

Just do it a step at a time:

 

(5+m)²+(m-2)(m+2)-2m(m+5):

 

(5+m)² = 25 + 10m + m²

(m-2)(m+2) = m² - 4

-2m(m+5) = -2m² - 10m

 

Add all the like terms together.  All the m² terms cancel out.  So do the m terms.  You're just left with 25 - 4 = 21

 

(c+3)²-2c(c-2)+(c-4)(c+4):

 

(c+3)² = c² + 6c + 9

-2c(c-2) = -2c² + 4c

(c-4)(c+4) = c² -16

 

The c² terms cancel out.  6c + 4c = 10c.  9 - 16 = -7.  So you're left with 10c - 7.