Answer:
See explanations below
Step-by-step explanation:
Given the system of equation
2x - 10 y = -30 ... 1
x - 5y = 20 ... 2
Step: From 2;
x = 20 + 5y ...3
Step 2: Substitute equation 3 into 1
2x - 10y = -30
2(5y+20) - 10y = -30
Open the bracket
10y + 40 - 10y = -30
10y - 10y + 40 = -30
0+40 = -30
40 = -30
The steps taken by Teri are correct all through. He didn't make any error whatsoever
10.
50+(2x)=20+(5x)
-20 -20
-2x -2x
30=3x
divide both sides by 3
10=x
Most textbooks interpret standard form of a quadratic function to be as follows:
f(x) =

In the function f(x) =

, notice we do not have a value for "c". Just place a "0" in for the c and you have standard form.
the criteria for standard form:
1. All like terms are combined
2. Degree must drop from left to right
3. The leading coefficient cannot be equal to zero.