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MArishka [77]
3 years ago
10

Solve for x x squared plus 4X minus 21 equals 0

Mathematics
2 answers:
iren2701 [21]3 years ago
7 0

Answer:

x = 3\\x = -7

Step-by-step explanation:

We have the following quadratic equation

x^2 + 4x - 21 =0

To solve the equation we must factor it.

To factor the equation we must find 2 numbers b and c that when adding them, you obtain as result 4 (c + b = 4) and when multiplying them, you obtain as result -21 (c * b = -21).

Then the polynomial will be factored in the following way:

(x+c)(x + b) = 0

You can verify that the numbers that meet this condition are:b = 7\\c = -3

So

x^2 + 4x - 21 =(x-3)(x + 7)=0

Finally the solutions are:

x = 3\\x = -7

suter [353]3 years ago
3 0

Answer:

x = -7 and x = 3

Step-by-step explanation:

x² + 4x - 21 = 0 factors as follows:  (x + 7)(x - 3) = 0.

Then x = -7 and x = 3.

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Let E = {(x, y) e R2|xy > 0}. Determine whether E is a subspace of R2 . X3
gayaneshka [121]

Answer:

E is not a subspace of \mathbb{R}^2

Step-by-step explanation:

E is not a subspace of  \mathbb{R}^2

In order to see this, we must find two points (a,b), (c,d) in  E such that (a,b) + (c,d) is not in E.

Consider

(a,b) = (1,1)

(c,d) = (-1,-1)

It is easy to see that both (a,b) and (c,d) are in E since 1*1>0 and (1-)*(-1)>0.  

But (a,b) + (c,d) = (1-1, 1-1) = (0,0)

and (0,0) is not in E.

By the way, it can be proved that in any vector space all sub spaces must have the vector zero.

5 0
3 years ago
2x ​2 ​​ (9x ​2 ​​ −16)
xz_007 [3.2K]
Is the equation2x2(9x+2-16) if so you would do -16+2 first which is -14

Then multiply 2x2 equals 4

4(9x-14)

Multiply the 4 to 9x and -14

You get 36x-56
7 0
3 years ago
Does the ratio 15/12 and 5/4 form a proportion?
Tanya [424]

Answer:

yes

Step-by-step explanation:

5 times 3 is 15 and 12 and 15 and 12 divided  by  3 you will get 5/4

4 0
3 years ago
Similar to changes in elevation, temperature changes are often expressed as sums and differences of positive and negative ration
Sergio [31]

Answer:

39°F

Step-by-step explanation:

yeah thats is JDJDJDJDNSMS

5 0
3 years ago
Read 2 more answers
Identify the solution and graph of the given inequality.<br> 34 &gt; 3(2 − x)
Verizon [17]

Answer:

Solving the inequality we get x>-9.33

The graph is shown in figure attached.

Step-by-step explanation:

We need to solve the inequality: 34 > 3(2-x)

Solving:

34 > 3(2-x)\\

Switching the sides , reversing the inequality and  Multiply 3 with terms inside the bracket

3(2-x)

Subtract 6 from both sides

6-3x-6

Divide both sides by -3 and inequality will be reversed

\frac{-3x}{-3} >\frac{-28}{3} \\x>\frac{-28}{3}\\x>-9.33

Solving the inequality we get x>-9.33

The graph is shown in figure attached.

6 0
3 years ago
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