Answer: 20
Step-by-step explanation:
x+y=5
x-y=4
---------
x+y=5
x=4+y
--------
(4+y)+y=5
4+y+y=5
4+2y=5
2y=1
y=0.5
x=4.5
---------
x²-y²=(4.5)²-(0.5)²=20.25-0.25=20
First you simplify both sides
Multiply -1 by x and 7
-x-7-16=x-3
Subtract -16 from -7
-x+9=x-3
Add 3. To both sides
-x+12=x
Add x to both sides
12=2x
Divide both sides by 2
6=x
Answer:
Cos a = 3/8.
Step-by-step explanation:
If you want cos a you use the identity cos a = 1 / sec a,
so cos a = 1 / 8/3
= 3/8.
