Solve the Quadratic Equation: Find x in 4x^2 + 9x - 5 = 7 - 4x

Question

Solve the following equation:

4x2+9x5=74x 4x^2+9x-5=7-4x

Video Solution

Solution Steps

00:00 Find X
00:03 Arrange the equation so that the right side equals 0
00:09 Collect like terms
00:19 Identify the equation components
00:26 Use the quadratic formula
00:35 Substitute appropriate values and solve for X
00:45 Calculate the multiplications and squaring
01:07 Calculate the square root of 361
01:14 Find the two possible solutions
01:22 This is one solution
01:27 This is the second solution and the answer to the question

Step-by-Step Solution

Let's solve the equation 4x2+9x5=74x 4x^2 + 9x - 5 = 7 - 4x step by step:

  • Step 1: Move all terms to one side to form a standard quadratic equation.

We begin by subtracting 7 7 and adding 4x 4x to both sides of the given equation:

4x2+9x57+4x=0 4x^2 + 9x - 5 - 7 + 4x = 0

Combining like terms, we get:

4x2+13x12=0 4x^2 + 13x - 12 = 0

  • Step 2: Identify the coefficients a a , b b , and c c in the quadratic equation 4x2+13x12=0 4x^2 + 13x - 12 = 0 .

Here, a=4 a = 4 , b=13 b = 13 , and c=12 c = -12 .

  • Step 3: Apply the quadratic formula:

The quadratic formula is given by x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} .

Plugging in the values of a a , b b , and c c :

x=13±1324×4×(12)2×4 x = \frac{-13 \pm \sqrt{13^2 - 4 \times 4 \times (-12)}}{2 \times 4}

x=13±169+1928 x = \frac{-13 \pm \sqrt{169 + 192}}{8}

x=13±3618 x = \frac{-13 \pm \sqrt{361}}{8}

x=13±198 x = \frac{-13 \pm 19}{8}

  • Step 4: Solve for the possible values of x x .

We have two solutions:

For the positive case:

x1=13+198=68=34 x_1 = \frac{-13 + 19}{8} = \frac{6}{8} = \frac{3}{4}

For the negative case:

x2=13198=328=4 x_2 = \frac{-13 - 19}{8} = \frac{-32}{8} = -4

Therefore, the solutions are x1=34 x_1 = \frac{3}{4} and x2=4 x_2 = -4 .

Answer

x1=34 x_1=\frac{3}{4} x2=4 x_2=-4