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Alex787 [66]
3 years ago
9

Solve the system: {4x-7y=30, 4x-5y=90

Mathematics
1 answer:
Lerok [7]3 years ago
7 0

Answer:

x=60, y=30

Step-by-step explanation:

4x-7y=30

4x-5y=90

Subtract the equations

4x-7y=30-4x-5y=90

=2y=60

Solve 2y=60

Divide both sides by 2

2y/2=60/2

Simplify;

y=30

For 4x-7*30=30 for x

4x-7y*30=30

Multiply the numbers:7*30=210

4x-210=30

Add 210 to both sides

4x-210+210=30+210

Simplify;

4x=240

Divide both sides by 4

4x/4=240/4

Simplify

x=60

The solutions to the system of equations are:

x=60, y=30

Hope this helped!!!

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The roots of 2x^2-3x=4 are a and b. Find the simplest quadratic equation which has roots 1/a and 1/b
Tju [1.3M]
Find the roots

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we use hmm, completing the suare
2(x²-1.5x)=4
divide both sides by 2
x²-1.5x=2
take 1/2 of linear coeiftn and square it
-1.5/2=-0.75, (-0.75)²=0.5625
add that to both sides
x²-1.5x+0.5625=2+0.5625
factor perfect squaer trinomial
(x-0.75)²=2.5625
square root both sides, remember to take positive and negative square roots
x-0.75=+/-√2.5625
add 0.75 to both sides
x=0.75+/-√2.5625

the roots are x=0.75+√2.5625 and x=0.75-√2.5625

1/a and 1/b
1/(0.75+√2.5625) and 1/(0.75-√2.5625)

if the roots of a quadratic equation are r1 and r2 then it factors to
(x-r1)(x-r2)
so then we can factor our equation to be
(x-\frac{1}{0.75+\sqrt{2.5625}})(x-\frac{1}{0.75-\sqrt{2.5625}})

if we were to try and expand it, we would get
x²+0.75x-0.5
that's the simpliest equation with roots 1/a and 1/b where a and b are he roots of 2x²-3x=4


x²+0.75x-0.5 is answer
8 0
3 years ago
The diameter of a circle is 3.2 meters. Which is the circumference of the circle rounded to the nearest hundredth of a meter?
Paraphin [41]

Answer:

10.05 meters

Step-by-step explanation:

If the diameter is 3.2 meters, then the radius is 1.6 meters.

Use the circumference formula, C = 2\pir, and solve for C

C = 2\pir

C = 2\pi(1.6)

C = 3.2\pi

C = 10.05

So, to the nearest hundredth of a meter, the circumference is 10.05 meters

4 0
2 years ago
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