For these kinds of expressions use FOIL (first, outside, inside, last).
-2x • 9x = -18x^2
-2x • -3y = 6xy
8y • 9x = 72 xy
8y • -3y = -24y^2
Now combine them all:
-18x^2 + 78xy - 24y^2
Secant is the same as 1/cos so you can just write it as 1/2pi then you can put that into your calculator as 1/cos(2pi) and it equals 1.
Answer:
length = 8
width = 4
Step-by-step explanation:
Area = length x breadth
Let x represent the width
length = x + 4
32 = x × (x + 4)
32 = x² + 4x
x² + 4x - 32 = 0
solving using quadratic equation =
(x² - 4x) -32 + 8x
x = 4 or -8
since width cannot be a negative number, we would use 4
C , a relationship between two variables can be expressed by an equation in which one variable is equal to a constant.
Let S be the amount in a savings account.
Let m be the number of months.
General equation
S = 132 + 27m
Specific question
July is the 7th month of the year including both January and July.
S = 132 + 7*27
S = 132 + 189
S = 321
Reasonableness?
Good question. You could estimate an answer.
Start with 150 dollars and say that you add 25 a month.
7 * 25 = 175
S = 150 + 175 = 325 All of this was done in my head. Since the exact answer obtained using the formula is 321, I think that's pretty reasonable using my estimate is a guide.
