8th Grade Mental Math
What is the relationship?
The temperature outside and the amount of clothes a person wears.
Negative
What is the rule when reflecting over the x-axis?
The x value stays the same.
What is slope?
The rate of change.
rise/run
Is this a function?
(4,8) (3,6) (2,5) (4,8)
NO
Write an expression 17 less than thrice a number is 31
3x -17 = 31
Two angles that add up to 90 degrees
Complementary Angles
What is the x value of the y-intercepts coordinates? (Think about when looking at a table of values)
0. (0, y)
Conner eats 12 hotdogs in 6 mins. Brenda eats 8 hotdogs in 3 minutes.
If graphed, which person would have the steeper slope?
Brenda's slope would be steeper.
Move the equation into slope-intercept form.
2x + y =5
y = -2x +5
Solve the equation x3 - 2 x + 5 =7965
x=20
2(3x+5)
6x+10
Identify the slope and y-intercept.
y= 2x+3
slope = 2
y-intercept = 3
If a line is decreasing then it's slope is __________
Negative
y = 1/2x + 4: What is the slope?
1/2
A triangle has sides that measure 9, 12, and 15. Is it a right triangle?
Yes
8(4x-9)+12
32x-60
What is the formula for finding slope?
y2 - y1 Divided by x2 - x1
Mrs. Knoll had 30 loaves of bread and sold 3 loaves per hour. Write an equation to represent this.
y = -3x +30
y = x - 3: What is the y-intercept?
-3
Evaluate the given equation for x.
(x2 + 5) / x+5 = 21
x=25
2(3-3x)=2x+22
x= -2
What is the formula for slope-intercept form?
y = mx + b
When Timmy was first born, he weighed 8.5 pounds. Every month he gained 1.5 pounds. Write an equation in slope intercept form that represents this situation.
y = 1.5x + 8.5
What is the range?
(2,3)(3,-1)(-1,1)
(-1, 1, 3)
Two angles that add up to 180 degrees
Supplementary Angles