Answer:
Step-by-step explanation:
i Don't now how to explain the answer
There are 5 solutions for this system.
x^2 + 4y^2 = 100 ____1
4y - x^2 = -20 ____2
Add both 1 & 2 together. x^2 gets cancelled
4y^2 + 4y = 80 (send 80 to the other side and divide by 4)
Then equation the becomes : y^2 + y -20 =0
Now factorise the equation: (y+5) (y-4) = 0
Solve for y : y = -5 and y = 4
Using the values of y to find the values of x. From equation 1:
x^2 = 100 - 4y^2 x = /100 - 4y^2 (/ means square root) Replace values of y
y = -5, x = /100 - 4(-5)^2 = /100 - 100 = 0
y = 4, x = /100 - 4(4)^2 = / 100 - 64 = /36 = -6 or 6
Thus we have 6 solutions y = -5, 4 and x = -6, 0, 6
$20.70
Eighteen dollars
Fifteen percent of eighteen is 2.7
(.15 X 18)+18
Answer:
His estimate is somewhat low.
Step-by-step explanation:
The total bill is $9.50 +3.50 = $13.00. The estimated tip is 15% of $10, so Jamal needs to add 15% of $3, or $0.45, to his estimate to leave a tip equal to 15% of the bill.
The tip Jamal has calculated is about 11.5% of the bill. (1.50/13.00 ≈ 0.1154)
The tip Jamal wants to leave is $1.95. (0.15·13.00 = 1.95)
