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Which two of the following equations could be solved using the quadratic formula?

A. [tex]\( 5x^3 - 3x + 10 = 2x^2 \)[/tex]
B. [tex]\( 2x^2 - 3x + 10 = 2x + 21 \)[/tex]
C. [tex]\( 5x^2 + 2x - 4 = 2x^2 \)[/tex]
D. [tex]\( 2x^2 - 6x - 7 = 2x^2 \)[/tex]


Sagot :

Sure, let's analyze each equation one by one to determine if it can be simplified to a quadratic equation, and then see which ones can be solved using the quadratic formula.

1. Equation A: [tex]\(5 x^3 - 3 x + 10 = 2 x^2\)[/tex]

Rearrange and simplify:
[tex]\[ 5 x^3 - 3 x + 10 - 2 x^2 = 0 \][/tex]
[tex]\[ 5 x^3 - 2 x^2 - 3 x + 10 = 0 \][/tex]
This is a cubic equation (degree 3), so it cannot be solved using the quadratic formula.

2. Equation B: [tex]\(2 x^2 - 3 x + 10 = 2 x + 21\)[/tex]

Rearrange and simplify:
[tex]\[ 2 x^2 - 3 x + 10 - 2 x - 21 = 0 \][/tex]
[tex]\[ 2 x^2 - 5 x - 11 = 0 \][/tex]
This is a quadratic equation (degree 2), so it can be solved using the quadratic formula.

3. Equation C: [tex]\(5 x^2 + 2 x - 4 = 2 x^2\)[/tex]

Rearrange and simplify:
[tex]\[ 5 x^2 + 2 x - 4 - 2 x^2 = 0 \][/tex]
[tex]\[ 3 x^2 + 2 x - 4 = 0 \][/tex]
This is a quadratic equation (degree 2), so it can be solved using the quadratic formula.

4. Equation D: [tex]\(2 x^2 - 6 x - 7 = 2 x^2\)[/tex]

Rearrange and simplify:
[tex]\[ 2 x^2 - 6 x - 7 - 2 x^2 = 0 \][/tex]
[tex]\[ -6 x - 7 = 0 \][/tex]
[tex]\[ -6 x = 7 \][/tex]
[tex]\[ x = -\frac{7}{6} \][/tex]
This is a linear equation (degree 1), so it cannot be solved using the quadratic formula.

So, the equations that can be solved using the quadratic formula are:

B. [tex]\(2 x^2 - 3 x + 10 = 2 x + 21\)[/tex]

C. [tex]\(5 x^2 + 2 x - 4 = 2 x^2\)[/tex]