Solve (x+4)(3x-1/4) = 3(x²+5): Complete Quadratic Equation Guide

Question

(x+4)(3x14)=3(x2+5) (x+4)(3x-\frac{1}{4})=3(x^2+5)

x=? x=?

Video Solution

Solution Steps

00:00 Solve
00:04 Open parentheses properly and multiply each factor by each factor
00:25 Open parentheses properly and multiply by each factor
00:40 Solve each multiplication separately
00:57 Simplify what's possible
01:01 Collect terms
01:13 Isolate the unknown X
01:25 Convert from number and fraction to fraction
01:30 Calculate the numerator multiplication
01:34 Multiply by denominator to eliminate the fraction
01:48 Isolate the unknown X
01:56 Break down 64 into 47 plus 17
02:04 Break down one fraction into a whole number and remainder
02:14 And this is the solution to the question

Step-by-Step Solution

To solve the equation (x+4)(3x14)=3(x2+5) (x+4)(3x-\frac{1}{4}) = 3(x^2+5) , follow these steps:

  • Step 1: Expand the left side of the equation
    (x+4)(3x14)(x + 4)(3x - \frac{1}{4})

Using the distributive property:

x(3x)+x(14)+4(3x)+4(14) x(3x) + x(-\frac{1}{4}) + 4(3x) + 4(-\frac{1}{4})

=3x2x4+12x1 = 3x^2 - \frac{x}{4} + 12x - 1

  • Step 2: Simplify the expanded left side
    Combine like terms:

3x2+(12xx4)1 3x^2 + \left(12x - \frac{x}{4}\right) - 1

Convert x4\frac{x}{4} to a common denominator: 48x4x4=47x4\frac{48x}{4} - \frac{x}{4} = \frac{47x}{4}

Thus, the left side is: 3x2+47x41 3x^2 + \frac{47x}{4} - 1

  • Step 3: Simplify the right side
    3(x2+5)3(x^2 + 5)

=3x2+15 = 3x^2 + 15

  • Step 4: Set the simplified expressions equal and solve for x x

3x2+47x41=3x2+15 3x^2 + \frac{47x}{4} - 1 = 3x^2 + 15

Subtract 3x23x^2 from both sides:

47x41=15 \frac{47x}{4} - 1 = 15

Add 1 to both sides:

47x4=16 \frac{47x}{4} = 16

Multiply both sides by 4 to clear the fraction:

47x=64 47x = 64

  • Step 5: Solve for x x

x=6447 x = \frac{64}{47}

Express 6447\frac{64}{47} as a mixed number:

x=11747 x = 1\frac{17}{47}

Therefore, the solution to the equation is x=11747 x = 1\frac{17}{47} .

Answer

11747 1\frac{17}{47}