
We know that : (a - b)(a + b) = a² - b²

We know that : 1 - sin²x = cos²x



We know that : sec²x = 1 + tan²x







Answer:
Step-by-step explanation:
-15 times -5 = 75
-15 + -5 = -20
Answer: 
Step-by-step explanation:





Yes. I believe so. If u solve the equations you get x=1/2 and y=-1
Answer:
Hi
Step-by-step explanation:
Is there like a multiple choice so I could answer it:)