Answer:
8.06
Step-by-step explanation:
Use the Pythagorean theorem:

The hypotenuse is always the slanted side, or c (x in this picture), but the other numbers can be interchanged. Doesn't matter.
Plug the numbers 4 and 7 into the formula.

Now evaluate them to get 
16+49=65
To get c, take the square root of 65

Answer:
x=8,y=-1
Step-by-step explanation:
x-2y=10
x=10+2y
10+2y+3y=5
5y=-5
y=-1
x-2(-1)=10
x=8
Answer:
4*10^-6
Step-by-step explanation:
Answer:
3. - 8n² -8n + 3
Step-by-step explanation:
(4n^4 - 8n +4) - (8n² + 4n^4 +1)
Firstly, open the brackets.
= 4n^4 - 8n +4 - 8n² - 4n^4 - 1
Now, group like terms.
= 4n^4 - 4n^4 - 8n² -8n - 1 + 4
4n^4 - 4n^4 cancel out with each other since one is negative and the other is positive. So we're left with - 8n² -8n - 1 + 4
= - 8n² -8n - 1 + 4
= - 8n² -8n + 3