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3 years ago

Does 65-(45-20)equal (65-45)-20? how do you know?

Mathematics

2 answers:

tresset_1 [31]3 years ago

5 0

Answer:

No, the expression 65-(45-20) is not equal to (65-45)-20.

Step-by-step explanation:

Consider the provided expression.

Consider the expression: 65-(45-20)

Solve the above expression as shown.

65-(45-20)

65-(25)

65-25

Now consider the second expression.

(65-45)-20

20-20

Now compare both the result.

40≠0

Hence, the expression 65-(45-20) is not equal to (65-45)-20.

quester [9]3 years ago

4 0

No, it does not. 65-(45-20) is equal to 40, because you subtract 45-20 before because of the parentheses. When you do that, you get 25 then subtract 65-25, then get 40. Then, if you subtract 65-45 first and get 25, then subtract 25-20, you'll get 5.

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Semicircles

Studentka2010 [4]

Answer:

The area of the shaded portion of the figure is $9.1\ cm^2$

Step-by-step explanation:

see the attached figure to better understand the problem

we know that

The shaded area is equal to the area of the square less the area not shaded.

There are 4 "not shaded" regions.

step 1

Find the area of square ABCD

The area of square is equal to

$A=b^2$

where

b is the length side of the square

we have

$b=4\ cm$

substitute

$A=4^2=16\ cm^2$

step 2

We can find the area of 2 "not shaded" regions by calculating the area of the square less two semi-circles (one circle):

The area of circle is equal to

$A=\pi r^{2}$

The diameter of the circle is equal to the length side of the square

$r=\frac{b}{2}=\frac{4}{2}=2\ cm$ ---> radius is half the diameter

substitute

$A=\pi (2)^{2}$

$A=4\pi\ cm^2$

Therefore, the area of 2 "not-shaded" regions is:

$A=(16-4\pi) \ cm^2$

and the area of 4 "not-shaded" regions is:

$A=2(16-4\pi)=(32-8\pi)\ cm^2$

step 3

Find the area of the shaded region

Remember that the area of the shaded region is the area of the square less 4 "not shaded" regions:

$A=16-(32-8\pi)=(8\pi-16)\ cm^2$

---> exact value

assume

$\pi =3.14$

substitute

$A=(8(3.14)-16)=9.1\ cm^2$

8 0

3 years ago

Y=2X+1 FOR X=-3,-1,0,2

Ahat [919]

When x = -3 y = -5
When x = -1 y = -1
When x = 0 y = 1
When x = 2 y = 5

6 0

3 years ago

Plz help me get the answer right

Jobisdone [24]

Three of the points that are on the graph are

(-1.38,2.05)= y=11+5x/2
(0,5.5)= y-intercept, (0,11/2)
(-2.2,0)= x-intercept, (-11/5,0)

8 0

3 years ago

A construction company showed that the strength, y, of concrete, measured

Vilka [71]

Answer:

a) y-intercept = 17; initial design strength percentage

b) slope = 2.8; increase in that percentage each day

c) 29.6 days to 100% design strength

Step-by-step explanation:

a, b) The equation is in the form called "slope-intercept form."

y = mx + b

where the slope is m, and the y-intercept is b.

Your equation has a slope of 2.8 and a y-intercept of 17.

The y-intercept is the percentage of design strength reached 0 days after the concrete is poured. The strength of the concrete when poured is 17% of its design strength.

The slope is the percentage of design strength added each day after the concrete is poured. The concrete increases its strength by 2.8% of its design strength each day after it is poured.

c) To find when 100% of design strength is reached, we need to solve for x:

100 = 2.8x +17

83 = 2.8x

83/2.8 = x ≈ 29.6

The concrete will reach 100 percent of its design strength in about 30 days.

8 0

3 years ago

Which expression is NOT equal to 125? (1 point)

likoan [24]

The correct answer for this question is this one: "B. the quotient 5 cubed over 5 to the fourth, raised to the negative 3 power"

<span>A. 5 times the quotient 5 cubed over two-fifths, raised to the second power
B. the quotient 5 cubed over 5 to the fourth, raised to the negative 3 power
C. 5 to the negative 2 over 5 to the negative 5
E. 5 times the quotient 5 to the 5 over 5 cubed</span>

3 0

3 years ago