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Romashka-Z-Leto [24]
3 years ago
11

Marcel made an error when he used the distributive property to solve the problem shown. Which sentence describes the error?

Mathematics
2 answers:
BigorU [14]3 years ago
7 0
A.In Step 2, 90 should be multiplied by the quantity 10 – 12, not by 10.

correct:
90(10 - 12) = 90 · 10 - 90 · 12 or 90(10 - 12) = 90 · (-2)
andrey2020 [161]3 years ago
7 0

Answer:

i Think it  B i an not sure

Step-by-step explanation:

You might be interested in
Prove that sin3a-cos3a/sina+cosa=2sin2a-1
Sloan [31]

Answer:

\frac{sin(3a)-cos(3a)}{sin(a)+cos(a)} =2sin(2a)-1

Step-by-step explanation:

we are given

\frac{sin(3a)-cos(3a)}{sin(a)+cos(a)} =2sin(2a)-1

we can simplify left side and make it equal to right side

we can use trig identity

sin(3a)=3sin(a)-4sin^3(a)

cos(3a)=4cos^3(a)-3cos(a)

now, we can plug values

\frac{(3sin(a)-4sin^3(a))-(4cos^3(a)-3cos(a))}{sin(a)+cos(a)}

now, we can simplify

\frac{3sin(a)-4sin^3(a)-4cos^3(a)+3cos(a)}{sin(a)+cos(a)}

\frac{3sin(a)+3cos(a)-4sin^3(a)-4cos^3(a)}{sin(a)+cos(a)}

\frac{3(sin(a)+cos(a))-4(sin^3(a)+cos^3(a))}{sin(a)+cos(a)}

now, we can factor it

\frac{3(sin(a)+cos(a))-4(sin(a)+cos(a))(sin^2(a)+cos^2(a)-sin(a)cos(a)}{sin(a)+cos(a)}

\frac{(sin(a)+cos(a))[3-4(sin^2(a)+cos^2(a)-sin(a)cos(a)]}{sin(a)+cos(a)}

we can use trig identity

sin^2(a)+cos^2(a)=1

\frac{(sin(a)+cos(a))[3-4(1-sin(a)cos(a)]}{sin(a)+cos(a)}

we can cancel terms

=3-4(1-sin(a)cos(a))

now, we can simplify it further

=3-4+4sin(a)cos(a))

=-1+4sin(a)cos(a))

=4sin(a)cos(a)-1

=2\times 2sin(a)cos(a)-1

now, we can use trig identity

2sin(a)cos(a)=sin(2a)

we can replace it

=2sin(2a)-1

so,

\frac{sin(3a)-cos(3a)}{sin(a)+cos(a)} =2sin(2a)-1


7 0
3 years ago
Read 2 more answers
Find the product.<br> (4x - 3y) (2x + y)
antoniya [11.8K]

Answer:

8x^2 - 2xy + 3y^2

Step-by-step explanation:

Use the FOIL method

8x^2 + 4xy - 6xy + 3y^2

8x^2 - 2xy + 3y^2

7 0
3 years ago
Will give first person to answer brainliest!! At a local baseball game, tickets cost $4 for adults and $2 for students. If there
S_A_V [24]

Answer:

let x adult and y student attended

x+y= 94

x=94-y

again

4x+2y = 294                               53 adults and 41 student attended

376-4y+2y =294                                           the  event

2y =82

y=41

substituting the value of y in

x+y =94

x= 94-41 = 53

Step-by-step explanation:

8 0
3 years ago
A Galapagos cactus finch population increases by half every decade. The number of finches is
Angelina_Jolie [31]

Answer:

The number of fringes at d=-2 is given as 20.

Step-by-step explanation:

Question

A Galapagos cactus finch population increases by half every decade. The number of finches is modeled by the expression

,

where d is the number of decades after the population was measured. Evaluate the expression for d = −2

Given :

The number of  finches is modeled by the expression  :

⇒ 45\cdot1.5^d

where d is the number of decades after the population was measured.

To evaluate the expression for d=-2

Solution:

In order to evaluate the given expression to find the number of finches at d=-2, we will plugin -2 for d in the expression and simplify it.

Plugging in d=-2 in the expression:

⇒ 45\cdot 1.5^{-2}

Using negative exponent property. [a^{-x}=\frac{1}{a^x}

⇒ 45\cdot \frac{1}{1.5^2}

⇒ 45\cdot \frac{1}{2.25}

⇒ 20   (Answer)

Thus, the number of fringes at d=-2 is given as 20.

This means the number of fringes two decades ago was 20.

6 0
3 years ago
21 marbles out of N are blue; probability of getting a blue one = 30%
MissTica
Probability=\frac{desired}{total}
0.3=\frac{21}{N}
0.3N=21
N=\frac{21}{0.3}
N=70

There are 70 total marbles. 
4 0
3 years ago
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