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lidiya [134]
3 years ago
13

Identify the variable(s), set up your equation(s), and solve. Richard has an elder sister who is twice his age and a younger sis

ter who is two years younger than him. If the product of his sisters' ages is 70, how old is Richard?
Mathematics
1 answer:
alexdok [17]3 years ago
3 0

Answer:

7 years

Step-by-step explanation:

Given that:

Let Richard's age = x

Elder sister's age = 2x

Youngwr sister's age = x - 2

Product of sisters ages = 70

2x * (x - 2) = 70

2x² - 4x = 70

2x² - 4x - 70 = 0

x² - 2x - 35 = 0

x² - 7x + 5x - 35 = 0

x(x - 7) +5(x - 7) = 0

(x - 7) or (x + 5) = 0

x = 7 or x = - 5

X can't be negative

Hence, x = 7

Richard is 7 years

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Select the correct answer.
BaLLatris [955]

Answer:

80

Step-by-step explanation:

in the figure above, angle 100 degrees is corresponding to the angle co - interior to angle x

that is

if we put an angle that is at the upper left of x, we can call that y which is corresponding to 100 degrees

since y is corresponding to 100 degrees, it automatically becomes the same as 100 degrees

therefore y=100

now, from the first line above, we know that x and y are co-interior which means that they both add up to 180 degrees

that is

x+y=180

we know that y = 100

therefore,

x+100=180

collect like terms and

x = 180-100

therefore,

x= 80

thank you!!

7 0
3 years ago
Z=5x-11y ?<br><br> and-2-5v &lt; 8
velikii [3]

Answer:

Step-by-step explanation: v> -2 the > has a line under it

3 0
3 years ago
1 - 5/6 &lt; 3x + 5/6 -2x
Romashka-Z-Leto [24]

Answer:

x>

−2

3

Step-by-step explanation:

6 0
3 years ago
Solve the system of equations by using substitution.<br> x+8y=-2<br> x-3y=20
zysi [14]

Answer:

(14, -2)

Step-by-step explanation:

To solve by using substitution, begin by solving for a variable in the first equation. Let's solve for x:

x+8y=-2\\x=-2-8y

Now we know what <em>x</em> equals. Let's substitute this into the second equation:

x-3y=20\\(-2-8y)-3y=20

We can then simplify:

-2-8y-3y=20 Given equation

-2-11y=20 Combine y terms

-11y=22 Add 2

y=-2 Divide by -11

So, we now know the value of y = -2.

To find the value of X, we can substitute the value of Y into one of the equations. Let's use the first one:

x+8y=-2

x+8(-2)=-2 Substitute for y

x-16=-2 Distribute 8

x=14 Add 16

So, we now know the value of x = 14.

Therefore, we know a solution to the system of equations is (14, -2).

4 0
3 years ago
1. x=1/(root3-root2). find rootx-(1/rootx) 2. if x=[root(a+2b)+root(a-2b)]/[root(a+2b)-root(a-2b]. show that bx^2-ax+b=0
timofeeve [1]
1. x = 1/ ( \sqrt{3} -  \sqrt{2)} = \sqrt{3}+  \sqrt{2};
 ( \sqrt{x} -1/ \sqrt{x} )^{2} = x + 1/x - 2 = = 
6 0
3 years ago
Read 2 more answers
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