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2 years ago

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The total use of electricity in the United States was 0.4 trillion kilowatt-hours in 1950 and about 2.8 trillion kilowatt-hours

in 1990. How many times more electricity was there in 1999 than 1950? Use scientific notation

1 answer:

lora16 [44]2 years ago

3 0

Answer: 7

Step-by-step explanation:

Scientific notation is a method that is used in very large numbers or when we've very small numbers. The number given will be multiplied by its power of 10. In this case,

2.8 trillion = 2,800,000,000,000

= 2.8 × 10^12

0.4 trillion = 400,000,000,000

= 4 × 10^11

Therefore, the times more electricity was there in 1999 than 1950 will be:

= (2.8 × 10^12) / (4 × × 10^11)

= (2.8/4) / (10^12 - 11)

= 0.7 × 10

= 7 times

There were 7 times more electricity that was there in 1999 than 1950.

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3 years ago

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Which equation is y = –6x^2 + 3x + 2 rewritten in vertex form? y = negative 6 (x minus 1) squared + 8 y = negative 6 (x + one-fo

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Answer:

$y = -6(x - \frac{1}{2})^2 -\frac{7}{2}$

Step-by-step explanation:

Given:

$y = -6x^2 + 3x + 2$

Required

Rewrite in vertex form

The vertex form of an equation is in form of: $y = a(x - h)^2+ k$

Solving: $y = -6x^2 + 3x + 2$

Subtract 2 from both sides

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Factorize expression on the right hand side by dividing through by the coefficient of x²

$y - 2 = -6(x^2 + \frac{3x}{-6})$

$y - 2 = -6(x^2 - \frac{3x}{6})$

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Get a perfect square of coefficient of x; then add to both sides

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<em>Rough work</em>

The coefficient of x is $\frac{-1}{2}$

It's square is $(\frac{-1}{2})^2 = \frac{1}{4}$

Adding inside the bracket of $-6(x^2 - \frac{x}{2})$ to give: $-6(x^2 - \frac{x}{2} + \frac{1}{4})$

To balance the equation, the same expression must be added to the other side of the equation;

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The expression becomes

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$y - 2 -\frac{6}{4}= -6(x^2 - \frac{x}{2} + \frac{1}{4})$

$y - 2 -\frac{3}{2}= -6(x^2 - \frac{x}{2} + \frac{1}{4})$

Factorize the expression on the right hand side

$y - 2 -\frac{3}{2}= -6(x - \frac{1}{2})^2$

$y - (2 +\frac{3}{2})= -6(x - \frac{1}{2})^2$

$y - (\frac{4+3}{2})= -6(x - \frac{1}{2})^2$

$y - (\frac{7}{2})= -6(x - \frac{1}{2})^2$

$y +\frac{7}{2} = -6(x - \frac{1}{2})^2$

Make y the subject of formula

$y = -6(x - \frac{1}{2})^2 -\frac{7}{2}$

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3 years ago

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postnew [5]

Answer:

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Let "a number" = x

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First add 4 to both sides:

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Isolate the variable, x. Divide 8 from both sides:

(48)/8 = (8x)/8

x = 48/8

x = 6

6 is your answer.

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Pls. see attachment.

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Answer:

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Step-by-step explanation:

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