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2 years ago

Is -7 + 9= 9 + 7 true, false or open

2 answers:

6 0

$-7 + 9 \neq 9 + 7$

$2 \neq 17$

When you add a positive number and a negative number, you get a positive, but the number is smaller. If you add two positive numbers, then of course, you're going to get a positive number as an answer. But overall, this is false.

True [87]2 years ago

5 0

That's false -7+9=2 and 7+9=18

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90=20+70 use the distributive property and the GCF OF 20 and 70 to write another related expression for 90 could you write anoth

juin [17]

90 = 20 + 70.....GCF of 20 and 70 is 10
90 = 10(2 + 7) <==

can u write another expression using a different common factor...yes
90 = 20 + 70.....common factor is 5
90 = 5(4 + 14) <==

8 0

3 years ago

Find the area of the largest rectangle (with sides parallel to the coordinate axes) that can be inscribed in the region enclosed

garik1379 [7]

F(x) = 18-x^2 is a parabola having vertex at (0, 18) and opening downwards.
g(x) = 2x^2-9 is a parabola having vertex at (0, -9) and opening upwards.
By symmetry, let the x-coordinates of the vertices of rectangle be x and -x => its width is 2x.
Height of the rectangle is y1 + y2, where y1 is the y-coordinate of the vertex on the parabola f and y2 is that of g.
=> Area, A
= 2x (y1 - y2)
= 2x (18 - x^2 - 2x^2 + 9)
= 2x (27 - 3x^2)
= 54x - 6x^3
For area to be maximum, dA/dx = 0 and d²A/dx² < 0
=> 54 - 18x^2 = 0
=> x = √3 (note: x = - √3 gives the x-coordinate of vertex in second and third quadrants)

d²A/dx² = - 36x < 0 for x = √3
=> maximum area
= 54(√3) - 6(√3)^3
= 54√3 - 18√3
= 36√3.

4 0

3 years ago

One airline carried 3,720 people on 31 flights between Portland and Los Angeles. If there were the same number on each flight, h

kondor19780726 [428]

Divide total people by total flights:

3720/31 = 120

There was 120 people on each flight

7 0

3 years ago

A local car dealer claims that 25% of all cars in San Francisco are blue. You take a random sample of 600 cars in San Francisco

sammy [17]

Answer:

No, we can't reject the dealer's claim with a significance level of 0.05.

Step-by-step explanation:

We are given that a local car dealer claims that 25% of all cars in San Francisco are blue.

You take a random sample of 600 cars in San Francisco and find that 141 are blue.

Let p = proportion of all cars in San Francisco who are blue

SO, Null Hypothesis, $H_0$ : p = 25% {means that 25% of all cars in San Francisco are blue}

Alternate Hypothesis, $H_A$ : p $\neq$ 25% {means that % of all cars in San Francisco who are blue is different from 25%}

The test statistics that will be used here is One-sample z proportion statistics;

T.S. = $\frac{\hat p-p}{{\sqrt{\frac{\hat p(1-\hat p)}{n} } } } }$ ~ N(0,1)

where, $\hat p$ = sample proportion of 600 cars in San Francisco who are blue = $\frac{141}{600}$ = 0.235

n = sample of cars = 600

So, test statistics = $\frac{0.235-0.25}{{\sqrt{\frac{0.235(1-0.235)}{600} } } } }$

= -0.866

Now at 0.05 significance level, the z table gives critical values of -1.96 and 1.96 for two-tailed test. Since our test statistics lies within the range of critical values of z so we have insufficient evidence to reject our null hypothesis as it will not fall in the rejection region due to which we fail to reject our null hypothesis.

Therefore, we conclude that 25% of all cars in San Francisco are blue which means the dealer's claim was correct.

4 0

3 years ago

A dilation with a scale factor of 1/3 is a reduction.

Natasha_Volkova [10]

That's true.
That will make the thing a third of its original size.

8 0

3 years ago