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Solve the equation $5x - 10 = 3x + 2$ - Junior Cycle Mathematics - Question 11 - 2015

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Solve the equation $5x - 10 = 3x + 2$. John says that $x = 4$ is a solution of $x^2 - 2x - 8 = 0$. Show that John is correct. Solve the simultaneous equations: $$x... show full transcript

Worked Solution & Example Answer:Solve the equation $5x - 10 = 3x + 2$ - Junior Cycle Mathematics - Question 11 - 2015

Step 1

Solve the equation $5x - 10 = 3x + 2$.

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Answer

To solve the equation, we first rearrange it:

5x10=3x+25x - 10 = 3x + 2

Subtracting 3x3x from both sides gives:

5x3x10=25x - 3x - 10 = 2

This simplifies to:

2x10=22x - 10 = 2

Now, we add 1010 to both sides:

2x=122x = 12

Finally, dividing both sides by 22 yields:

x = 6.$$

Step 2

Show that John is correct.

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Answer

To verify John's statement, we substitute x=4x = 4 into the equation:

422(4)8=0.4^2 - 2(4) - 8 = 0.

Calculating the left-hand side:

1688=0,16 - 8 - 8 = 0,

which simplifies to:

0=0.0 = 0.

Thus, John is correct since the equation holds true.

Step 3

Solve the simultaneous equations: $$x + y = 11$$ $$x - y = -5.$$

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Answer

We can start by expressing xx from the second equation:

x=y5.x = y - 5.

Substituting this into the first equation results in:

(y5)+y=11.(y - 5) + y = 11.

This simplifies to:

2y5=11.2y - 5 = 11.

Adding 55 to both sides gives:

2y=16,2y = 16,

which leads to:

y=8.y = 8.

Now substituting yy back into x=y5x = y - 5 gives:

x=85=3.x = 8 - 5 = 3.

Thus, the solution of the simultaneous equations is x=3x = 3 and y=8y = 8.

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