Question:25y²-1
answer​

(5y - 1)(5y + 1)

Step-by-step explanation:

Assuming you require the expression to be factorised.

25y² - 1 ← is a difference of squares and factors in general as

a² - b² = (a - b)(a + b) , then

25y² - 1

= (5y)² - 1²

= (5y - 1)(5y + 1)

Below.

Step-by-step explanation:

25y²-1

This is the difference of 2 squares and it factors to (5y - 1)(5y + 1).

yes

step-by-step explanation:

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18