for these you need to rearrange the equations and do substitutions.
#3 = if x+y=5 then you know x = 5-y
now substitute that equation for x in the 2nd one so x + 2y = 8 becomes
5-y + 2y = 8 2y - y becomes 1y which becomes y then subtract 5 from each side to get y =3
now replace y with 3 in the first equation x = 5-3 so x = 2
so (2,3) is the answer
same type of work for #4
2x-y=6 ,S0 y = 2X+6
so now you have 4x+2(2x+6)=-4
that becomes 4x +4x+12 = -4
8x+8 = 1, x =1
y = 2(1)-6 = -4
so answer is (1,-4)
The ratio of the area of the sector (S) to the area of the entire circle (C) is equal to the ratio of the angle subtended to form the sector (As) to the angle for the whole revolution (Ac)
S / C = As / Ac
Substituting the given,
S / 36 m² = 40 degrees / 360 degrees
Solving for S gives, S = 4. Thus, the area of the sector is 4 m².
Fraction with variable x in numerator and 6 in the denominator can written in the algebraic expression as 
Let's assume some number is n.
So, the sum of six and some number can be written as 6+n.
The product of six and some number can be written as 6*n.
The quotient of some number and six will be n/6.
The difference of six and some number will be 6-n.
A.) Integers are positive and negative counting numbers. So, in order to find the integer coefficients, round off the coefficients in the equation to the nearest whole number. The function for g(x) is:
g(x) = 3x²+3x
B.) Substitute x=4 to the two functions.
f(x) = 2.912345x²<span>+3.131579x-0.099999
</span>f(4) = 2.912345(4)²+3.131579(4)-0.099999
f(4) = 59.023837
g(x) = 3x²+3x
g(4) = 3(4)²+3(4)
g(4) = 60
C.) The percentage error is equal to:
Percentage error = |g(4) - f(4)|/f(4) * 100
Percentage error = |60 - 59.023837|/59.023837 * 100
Percentage error = 1.65%
D.) If x is a large number, for example x=10 or x=20, then g(x) would be an overestimate. This is because the value of x is raised to the power of 2. So, as the x increases, the corresponding function would increase exponentially. Even at x=4, g(x) is already an overestimate. What more for larger values of x? That means that the gap from the true answer f(x) would increase.
