We are going to make simultaneous equations.
x will be our $3 ice cream and y will be our $5 ice cream
Equation1 ---- x + y = 50 (the sum of all the ice creams they sell)
Equation 2 ---- 3x + 5y = 180 Sum of all the $3 and $5 ice creams is $180
Since we can't solve for both variables we will put one of the variables in terms of the other.
Take x+y=50 and subtract y from both sides. (I could have done subtracted x - it did not matter). Now we have x= ₋ y +50 (negative y +50)
Now I am going to take equation 2 and replace the x with -y +50
3 (-y +50) + 5y = 180
Now I will use the distributive law on the 3 and what's in the parentheses:
-3y + 150 + 5y = 180
Now I will combine like terms (the -3y and the 5y)
2y + 150 = 180
Now subtract 150 from both sides of the equation
2y = 30
Divide both sides by 2
and get y= 15 They sold 15 ice creams that cost $5 each
Since equation 1 is x+y=50 we can replace y with 15
x + 15 = 50 Now subtract 15 from both sides x = 35
Since x represents the $3 ice creams, they sold 35 of those.
Check:
35 X 3 = $105
15 x 5 = + <u>75
</u> $180
Answer:
11, 15, 26, 41, could be an answer
8 a) y=x² stretched vertically by 8
That means (0,0) stays (0,0), and (1,1) becomes (1,8) and (-1,1) becomes (-1,8)
Answer: y = 8x²
8 b) y=x² compressed vertically by 1/5
Answer: y = (1/5) x²
9.
y = ax² + k through (-1,3) and (3,-13)
That means
3 = a (-1)² + k
-13 = a (3²) + k
Subtracting,
16 = a - 9a = -8a
a = -2
3 = -2 + k
k = 5
y = -2x² + 5
Check:
-2(-1)^2 + 5 = 3, good
-2(3)^2+5 = -18 + 5 = -13, good
Answer: a = -2, k = 5