Answer:
D
Step-by-step explanation:
given the 2 equations
x + 2y = 27 → (1)
2x + 3y = 46 → (2)
Rearrange (1) expressing x in terms of y by subtracting 2y from both sides
x = 27 - 2y ← substitute into (2)
2(27 - 2y) + 3y = 46
54 - 4y + 3y = 46
54 - y = 46 ( subtract 54 from both sides )
- y = - 8 ( multiply both sides by - 1 )
y = 8 → D
Answer:
7.425 laps.
Step-by-step explanation:
That would be 378.925 - 371.5
= 7.425 laps,
Answer:
C. y = -4/5x - 2
Step-by-step explanation:
Graph the line using the slope and y-intercept, or two points.
Slope:
−
4
5
y-intercept:
(
0
,
−
2
)
x
y
−
5
2
0
0
−
2
Answer:
2.
Step-by-step explanation:
For #2, another way to word this question is: For which of the following trig functions is π/2 a solution? Well, go through them one by one. If you plug π/2 into sinθ, you get 1. This means that when x is π/2, y is 1. Try and visualize that. When y is 1, that means you moved off the x-axis; so y = sinθ is NOT one of those functions that cross the x-axis at θ = π/2. Go through the rest of them. For y = cos(π/2), you get 0. At θ = π/2, this function crosses the x-axis. For y = tanθ, your result is undefined, so that doesn't work. Keep going through them. You should see that y = secθ is undefined, y = cscθ returns 1, and y = cotθ returns 0. If you have a calculator that can handle trig functions, just plug π/2 into every one of them and check off the ones that give you zero. Graphically, if the y-value is 0, the function is touching/crossing the x-axis.
Think about what y = secθ really means. It's actually y = 1/(cosθ), right? So what makes a fraction undefined? A fraction is undefined when the denominator is 0 because in mathematics, you can't divide by zero. Calculators give you an error. So the real question here is, when is cosθ = 0? Again, you can use a calculator here, but a unit circle would be more helpful. cosθ = π/2, like we just saw in the previous problem, and it's zero again 180 degrees later at 3π/2. Now read the answer choices.
All multiples of pi? Well, our answer looked like π/2, so you can skip the first two choices and move to the last two. All multiples of π/2? Imagine there's a constant next to π, say Cπ/2 where C is any number. If we put an even number there, 2 will cut that number in half. Imagine C = 4. Then Cπ/2 = 2π. Our two answers were π/2 and 3π/2, so an even multiple won't work for us; we need the odd multiples only. In our answers, π/2 and 3π/2, C = 1 and C = 3. Those are both odd numbers, and that's how you know you only need the "odd multiples of π/2" for question 3.
