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Paha777 [63]
3 years ago
11

If you add the digits in a two-digit number and multiply the sum by 7, you get the original number. If you reverse the digits in

the two-digit number, the new number is 18 more than the sum of its two digits. What is the original number?
A.250,250
B.315,185
C.370,230
D.410,90
E.480,20
Mathematics
2 answers:
MariettaO [177]3 years ago
8 0
Let x be the first digit (ten's place) of the original number.
Let y be the second digit (one's place) of the original number.

(x + y)7 = original number
(x + y)7 = 10x + y
7x + 7y = 10x + y
6y = 3x

10y + x = (x + y) + 18
9y = 18
y = 2

6y = 3x
6(2) = 3x
12 = 3x
x = 4

x is the first digit, and y is the second digit, so the original number is 42.
kolbaska11 [484]3 years ago
3 0
The answer is A. 42

Solution:
Let x= ones digit, y=tens digit

1st condition (original number) : 7(x+y)=10y + x
2nd condition (new number by reversing the digits): 18+x+y=10x+y

simplifying:
1st condition: 6x=3y
2nd condition: x=2
substituting x=2 to 6x=3y
<span>y=4</span>
You might be interested in
6th grade math , help me please :)
sleet_krkn [62]

Answer:

A. Eric rode 2 more miles per week than Kim rode

Step-by-step explanation:

Number of miles Kim rode bicycle in 9 weeks = 135 miles

Let x be the number of miles per week.

135miles => 9 weeks

x miles => 1 week

x = \frac{135}{9}

x = 15

Kim rode the bicycle 15 miles per week

Number of miles Eric rode bicycle in 6 weeks = 102 miles

Let x be the number of miles per week Eric rides the bicycle.

102 miles => 6 weeks

x miles => 1 week

x = \frac{102}{6}

x = 17

Kim rode the bicycle 17 miles per week

<em>Comparing the number of miles per week they rode, we would conclude that: "Eric rode 2 more miles per week than Kim rode".</em>

7 0
3 years ago
Find the value of x if 9^1/2 • 9^1/2 = x^√81
mario62 [17]

Answer:

(√9)^2x-1/2 = 1/81

3^2x-1/2 = 1/(3)⁴. (as √9 = 3)

3^2x-1/2 = 3^-⁴. (as 1/a^m = a^-m)

as base are equal exponents are equal

so 3 gets cancelled out

2x-1/2 = -4

(4x-1)/2 = -4

4x-1 = -8

x = -7/4

hope this helps

Step-by-step explanation:

3 0
3 years ago
What restrictions is there with a square root expression?
iris [78.8K]
There is one restriction: The number whose square root is needed can not be negative
8 0
3 years ago
Click an item in the list or group of pictures at the bottom of the problem and, holding the button down, drag it into the corre
bija089 [108]

Answer:

y²-2y+3

Step-by-step explanation:

We write the dividend, y³-y²+y+3, under the box and the divisor, y+1, to the left of the box.

We first divide y³ by y; this is y².  We write this above the box, over -y².  We multiply the divisor by y²:  

y²(y+1) = y³+y²

This goes under the divisor.  We then subtract:

(y³-y²)-(y³+y²) = -2y².  We then bring down the next term, y; this gives us -2y²+y.

We then divide -2y² by y; this is -2y.  This goes above the box beside the y² in the quotient.  We then multiply the divisor by -2y:

-2y(y+1) = -2y²-2y

We now subtract:

(-2y²+y)-(-2y²-2y) = 3y.  We bring down the last term, 3; this gives us 3y+3.  We divide 3y by y; this is 3.  This goes beside the -2y in the quotient.  We then multiply this by the divisor:

3(y+1) = 3y+3.  We then subtract:  (3y+3)-(3y+3) = 0

This makes the quotient y²-2y+3.

5 0
3 years ago
Read 2 more answers
I’ll mark brainest! Find all the real cube roots of -0.000125
Ymorist [56]

Answer:

-0.05

Step-by-step explanation:

This will become much easier if we can get the ugly decimal into a nice fraction form.

Start by recognising \frac{1}{8}=0.125. This is almost correct except the fraction is out by some number of factors of 10 (because the 125 part is correct but the number of 0s isn't).

\frac{1}{80} = 0.0125\\\frac{1}{800}=0.00125\\\frac{1}{8000}=0.000125

And hence we see that -0.000125=-\frac{1}{8000} and now the cube root becomes easy to compute:

\sqrt[3]{-0.000125} = \sqrt[3]{\frac{-1}{8000}} = \frac{\sqrt[3]{-1}}{\sqrt[3]{8000}} = \frac{-1}{20} = -0.05.

Advanced: You ask for <em>all </em>real cube roots. however the function y=\sqrt[3]{x} is described as <em>bijective</em>. This means for all x, there is only one y corresponding to it. (And also for all y there is only one x corresponding to that). This means there can only ever be one cube root of any real number.

4 0
3 years ago
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