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2 years ago

Why do you cross-multiply when you solve proportions?

1 answer:

5 0

Answer: The reason you cross multiply fractions is to compare them. Cross multiplying fractions tells us if the two fractions are equal or which one is greater. This is especially useful when you are working with larger fractions that you aren't sure how to reduce.

It works cause they have the same denominator

bruh

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Solve the equation using the quadratic formula : x^2-10x+25=18

Sever21 [200]

$x^2-10x+25=18 \\ \\x^2-10x+25-18 = 0\\ \\ x^2-10x+ 7 =0 \\ \\a=1 , b = -10 , c= 7 \\ \\ \Delta = b^{2}-4ac = (-10)^{2}-4*1*7=100-28 = 72 \\ \\\sqrt{\Delta }=\sqrt{72}= \sqrt{2*36} =\sqrt{36}*\sqrt{2} =6\sqrt{2}$

$x_{1}=\frac{-b-\sqrt{\Delta }}{2a} =\frac{10- 6\sqrt{2}}{2}=\frac{2(5-3\sqrt{2})}{2}= 5-3\sqrt{2}\\ \\x_{2}=\frac{-b+\sqrt{\Delta }}{2a} =\frac{10+ 6\sqrt{2}}{2}=\frac{2(5+3\sqrt{2})}{2}= 5+3\sqrt{2}$

$Answer : \ x= 5-3\sqrt{2} \ \ or \ \ x = 5+3\sqrt{2}$

8 0

3 years ago

10 points! How do I factor 8x^2-26x+15

Rufina [12.5K]

The AC method, also known as splitting the middle, can be shown like this:

8x^2 - 26x + 15

Check factors of 120.

1 * 120

-1 * -120

2 * 60

-2 * -60

3 * 40

-3 * -40

5 * 24

-5 * -24

6 * 20

-6 * -20 (these factors, when added together, are equal to the middle term, and thus splitting the middle term is possible.)

Split the middle term.

8x^2 - 6x - 20x + 15

Group in terms of 2.

(8x^2 - 6x) - (20x + 15)

Factor each binomial.

2x(4x - 3) - 5(4x - 3)

Rearrange the terms.

(2x - 5)(4x - 3)

6 0

3 years ago

Read 2 more answers

-6d=-42 can you help me solve please

eduard

Given the equation :

$-6d=-42$

So, to find d , divide both sides by ( -6 )

So,

$\begin{gathered} \frac{-6d}{-6}=\frac{-42}{-6} \\ \\ d=7 \end{gathered}$

Note: when we divide two negative numbers, the result will be a positive number

5 0

8 months ago

The sum of two numbers is 60 and the difference is 2 what are the numbers.

oksian1 [2.3K]

Let the two numbers be x and y
Then
x + y = 60
And
x - y = 2
x = y + 2
Putting the value of x in the first equation we get
x + y = 60
y + 2 + y= 60
2y + 2 = 60
2y = 60 - 2
2y = 58
y = 58/2
y = 29
Now putting the value of y in the first equation we get
x + y = 60
x + 29 = 60
x = 60 - 29
x = 31
So the value of the two numbers comes out to be 31 and 29. I hope the procedure is clear enough for you to understand.

7 0

3 years ago

Read 2 more answers

a tin mine is estimated to have tin reserves worth two million ringgit. if the monthly extraction is 5% of the value of the rese

andrew-mc [135]

Month_1 Value = Month_0 Value * 0.95

Month_2 Value = Month_1 Value * 0.95 = Moth_0 Value * 0.95*0.95 = Month_0 Value * 0.95^2

Month _n Value = Month_0 Value * (0.95)^n

After 2 years ==> n = 24

Month_24 Value = Month_0 Value * (0.95)^24 = 2,000,000 *(0.95)^24 = 583,978.05

6 0

3 years ago