Factorise fully
X^2 - 25​

(x+5)(x-5)

Step-by-step explanation:

x^2-25 = x^2 - 5^2 = (x+5)(x-5)

rule: a^2 - b^2 = (a+b)(a-b)

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

the answer is a.

step-by-step explanation:

in three games of golf, alex shot two under par four times.