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3 years ago

Evaluate the expression 2x^2 - x, when x = -3. Show all steps.

Mathematics

2 answers:

Alex_Xolod [135]3 years ago

5 0

Answer:

Step-by-step explanation:

2x² - x

2(-3)² - (-3)

2(9) + 3

18 + 3

V125BC [204]3 years ago

4 0

Answer:

Step-by-step explanation:

This is a substitution question,we are to substitute a given value in place of a certain letter

So let's solve

2x^2-x

And since x is given to be -3

So let's substitute

2(-3)^2-(-3)

2(9)-(-3)

18+3

So the final answer is 21

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The side lengths of the following right triangle 15,20 and 25, as shown below. The altitude from the right angle splits the hypo

kompoz [17]

Answer:

$h = 12$

$x = 9$

$y= 16$

Step-by-step explanation:

Given

The attached triangle

Required

Find h, x and y

Let the base of the triangle be 15.

So, the area is:

$A = \frac{1}{2} * 15 * 20$

$i.e\ height = 20$

$A = \frac{1}{2} * 300$

$A = 150$

Let the base of the triangle be 25.

So, the area is:

$A = \frac{1}{2} * 25 * h$

$i.e\ height = h$

$A = \frac{1}{2} * 25h$

Substitute $A = 150$

$\frac{1}{2}*25h = 150$

Solve for h

$h = \frac{150 *2}{25}$

$h = 6 *2$

$h = 12$

Considering the smallest triangle

$Hypotenuse = 15$

So:

$15^2 = h^2 + x^2$

$15^2 = 12^2 + x^2$

This gives:

$15^2 - 12^2 = x^2$

$81 = x^2$

Take square roots

$9 =x$

$x = 9$

Solving for y

$x + y = 25$

$y= 25 - x$

$y= 25 - 9$

$y= 16$

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2 years ago

Which of the following is the correct solution to the linear inequality shown below?

Georgia [21]

Correct answer is C.

Line $y=\frac{1}{3}x-2$ intersects y-axis at -2 and passes through the point (3,-1).

Line must be dashed, because the inequality sign is ">".

Point (0,0) must lie in the solution set because it satisfies inequality $y>\frac{1}{3}x-2$ .

$0\ \textgreater \ \frac{1}{3}\times 0-2
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