Solve (8x+9)(5-x)=31x+94: Distributive Property Application

Quadratic Recognition with No Real Solutions

Solve the equation using the distributive property:

(8x+9)(5x)=31x+94 (8x+9)(5-x)=31x+94

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:04 Open parentheses properly, multiply each factor by each factor
00:30 Calculate the products
00:57 Simplify what we can
01:10 Isolate X
01:24 No number squared can be negative, therefore there is no solution
01:30 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the equation using the distributive property:

(8x+9)(5x)=31x+94 (8x+9)(5-x)=31x+94

2

Step-by-step solution

To solve the equation (8x+9)(5x)=31x+94 (8x+9)(5-x) = 31x + 94 , we will use the distributive property. The steps are as follows:

  • Step 1: Apply the distributive property to the left-hand side.
    We do this by multiplying each term in the first binomial by each term in the second one:
  • (8x+9)(5x)=8x5+8x(x)+95+9(x)(8x + 9)(5 - x) = 8x \cdot 5 + 8x \cdot (-x) + 9 \cdot 5 + 9 \cdot (-x).
  • Simplify the terms:
    8x5=40x8x \cdot 5 = 40x,
    8x(x)=8x28x \cdot (-x) = -8x^2,
    95=459 \cdot 5 = 45,
    9(x)=9x9 \cdot (-x) = -9x.
  • Combine all like terms:
    The left-hand side becomes 8x2+40x+459x=8x2+31x+45-8x^2 + 40x + 45 - 9x = -8x^2 + 31x + 45.
  • Step 2: Compare both sides of the equation:
    We have 8x2+31x+45-8x^2 + 31x + 45 on the left-hand side and 31x+9431x + 94 on the right.
  • Step 3: Set the equation:
    8x2+31x+45=31x+94-8x^2 + 31x + 45 = 31x + 94.
  • Step 4: Subtract 31x31x from both sides:
    8x2+45=94-8x^2 + 45 = 94.
  • Step 5: Now subtract 45 from both sides:
    8x2=49-8x^2 = 49.
  • Step 6: Divide by 8-8:
    x2=498x^2 = -\frac{49}{8}.
  • Step 7: Evaluate the Result:
    The result x2=498x^2 = -\frac{49}{8} implies taking the square root of a negative number, which results in an imaginary number, thus indicating no real solution exists.

Therefore, the solution to the equation is: There is no solution to the equation.

3

Final Answer

There is no solution to the equation.

Key Points to Remember

Essential concepts to master this topic
  • Distribution: Multiply each term in first binomial by every term in second
  • Technique: Combine like terms: 40x9x=31x 40x - 9x = 31x on left side
  • Check: When x2=negative number x^2 = \text{negative number} , no real solution exists ✓

Common Mistakes

Avoid these frequent errors
  • Assuming every equation must have a solution
    Don't keep trying to solve when you get x2=498 x^2 = -\frac{49}{8} = impossible square root! This means the equation has no real solutions. Always recognize that negative values under square roots indicate no real solution exists.

Practice Quiz

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\( (3+20)\times(12+4)= \)

FAQ

Everything you need to know about this question

Why doesn't this equation have a solution?

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When we solve and get x2=498 x^2 = -\frac{49}{8} , we need the square root of a negative number. Since no real number squared gives a negative result, there's no real solution!

Did I make a mistake if I get no solution?

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No! Some equations genuinely have no real solutions. This is a valid mathematical result. Double-check your algebra, but don't assume you did something wrong.

How do I know when to stop trying to solve?

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Stop when you reach x2=negative number x^2 = \text{negative number} . This immediately tells you there's no real solution since square roots of negative numbers aren't real.

What's the difference between no solution and zero as a solution?

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No solution means the equation is impossible to satisfy with any real number. Zero as a solution means x=0 x = 0 makes the equation true - that's a valid answer!

Should I check my distributive property work?

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Yes! Verify: (8x+9)(5x)=40x8x2+459x=8x2+31x+45 (8x+9)(5-x) = 40x - 8x^2 + 45 - 9x = -8x^2 + 31x + 45 . Each multiplication must be correct before concluding no solution exists.

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