Question

Which of the following has a graph that is a straight line?

Equation 1: y = 2x + 7
Equation 2: y2 = x − 1
Equation 3: y = 2x2 + 4
Equation 4: y = 3x3

Answer 1

Use your knowledge to eliminate, what happens is you raise the x to a power??

Answer 2

@Awolflover1 @Hayhayz @SolomonZelman

Answer 3

idk

Answer 4

It curves...

Answer 5

im not sure that's why im on here asking

Answer 6

its ok, when you raise x to a power, it curves up or down depending on whether its positive or negative, raising y to a power is going to cause it to curve to the left or right, which means???

Answer 7

Does that help??

Answer 8

nope

Answer 9

If a graph curves, is it straight?

Answer 10

no

Answer 11

@mathmale

Answer 12

and x raised to a power makes it curve up and down, if it curves up and down is it straight??

Answer 13

this is very confusing

Answer 14

An equation has a straight line if its variables are alone or just multiplied by numbers.

If it has variables in the denominator, variables raised to a power, variables multiplied by variables, variables in roots, logarithms of variables, or other non-linear functions with variables, then its graph is not a straight line.

Answer 15

i think it's A or D is it one of those

Answer 16

First off, " Equation 2: y2 = x − 1" should be written as y^2 = x − 1. That " ^2 " indicates the "squaring function," which you've likely seen before.

Likewise, Equations 3 and 4 should be written

y = 2x^2 + 4

and

y = 3x^3


Here is how we classify these functions that involve powers of x:

x^0: constant function; graph is a horizontal line

x^1: linear function; graph is a straight line

x^2: quadratic function; graph is a parabola opening up

x^3: cubing function: graph is odd, begins in the 3rd quadrant, goes thru the origin and ends up in the 1st quadrant.

This may be more info that you were looking for, but trust me, you do need to know and be able to recognize these kinds of functions and their graphs.

Answer 17

With this info, can you now identify the function that has a straight line graph?

Equation 1: y = 2x + 7
Equation 2: y^2 = x − 1
Equation 3: y = 2x^2 + 4
Equation 4: y = 3x^3

Answer 18

im sooo confused -banging head on desk-

Answer 19

I'm sorry you're feeling confused. But there is basic info in every subject that we (meaning me as well as you) MUST learn.

Answer 20

Hint: x^1 and x are exactly the same.

Answer 21

If the highest power of x is 1, then the function is "linear" and the graph is a straight line.

Answer 22

Examples

1. Linear functions whose graphs are straight lines:

\(y = 2x + 5\)

\(2x + 5y = -2\)

\(y = -\sqrt 2 x\) <--- notice only the 2 is in the square root, not the x

\(\dfrac{1}{2} x + \dfrac{3}{4}y = \dfrac{\sqrt{55}}{21} \)

2. Non-linear functions whose graphs are not straight lines:

\(\dfrac{1}{x} = 5y\) <--- x in denominator

\(\sqrt{x + 4} = 2y - 5\) <--- x in root

\(2xy + 3x = 5y\) <--- product of variables

\(y = 2x^2 - 4\) <--- variable raised to a power

\(y = \log (2x) \) <--- logarithm of a variable

Answer 23

is it B?

Answer 24

a line has *no exponents" on the variables

which equation has no "little numbers" on the letters

Answer 25

Please, Ali, explain your reasoning.

Answer 26

i think it's B because it's a straight line it dosent curve

Answer 27

Right, and it's a straight line because of what else? Hint: Look at the exponent of x in the given equation.

Answer 28

There is no B. Do you mean
Equation 2: \(y^2 = x − 1\)
?

Answer 29

yes

Answer 30

but

Answer 31

a line has *no exponents" on the variables

an example of an exponent is the 2 next to the y

Answer 32

B's right?

Answer 33

What I see in Answer B is y^2=x-1.
Did you check the exponent of x in this equation? If not, please do so now.

Answer 34

do you see the \( y^2 \)
?
that makes it *NOT* a line

Answer 35

I should have said that if you see a power other than 1 on either x or y, the function is NOT linear.

Answer 36

Once again, pls review all four possible answers. Only one of them features an exponent of 1 on both x and y.

Answer 37

...or, no exponent at all. Earlier I explained to you that 1x^1 is the same as 1x or just x.