Answer:
Step-by-step explanation:
Adding and subtracting expressions:
a) M + (5x² -2xy) = 6x² +9xy - y²
M = 6x² + 9xy - y² - (5x² - 2xy)
Remove the parenthesis by mulplying each term of 5x² - 2xy by (-1) as (-1) is outside the parenthesis
= 6x² + 9xy - y² - 5x² + 2xy
Combine ( add or subtract) like terms.
= 6x² - 5x² + 9xy + 2xy - y²
= x² + 11xy - y²
Hint: Like terms have same variable with same power.
Here, like terms are (i) 6x² and (-5x²) (ii) 9xy and 2xy
b) (3xy - 4y²) - N = x² - 7xy + 8y²
3xy - 4y² = (x² - 7xy + 8y²) + N
3xy - 4y² - (x² - 7xy + 8y²) = N
3xy - 4y² - x² + 7xy - 8y² = N
3xy + 7xy -4y² - 8y² -x² = N
10xy -12y² - x² = N
Answer: N = 10xy - 12y² -x²
