Solve l^242-4 - ScanMath

Question

Simplify the expression

42 l^{2} - 4

Evaluate

l^{2} \times 42 - 4

Solution

42 l^{2} - 4

Show Solution

2 (21 l^{2} - 2)

Evaluate

l^{2} \times 42 - 4

Use the commutative property to reorder the terms

42 l^{2} - 4

Solution

2 (21 l^{2} - 2)

Show Solution

l_{1} = - \frac{42}{21}, l_{2} = \frac{42}{21}

Alternative Form

l_{1} \approx - 0.308607, l_{2} \approx 0.308607

Evaluate

l^{2} \times 42 - 4

To find the roots of the expression,set the expression equal to 0

l^{2} \times 42 - 4 = 0

Use the commutative property to reorder the terms

42 l^{2} - 4 = 0

Move the constant to the right-hand side and change its sign

42 l^{2} = 0 + 4

Removing 0 doesn't change the value,so remove it from the expression

42 l^{2} = 4

Divide both sides

\frac{42 l ^{2}}{42} = \frac{4}{42}

Divide the numbers

l^{2} = \frac{4}{42}

Cancel out the common factor 2

l^{2} = \frac{2}{21}

Take the root of both sides of the equation and remember to use both positive and negative roots

l = \pm \frac{2}{21}

Simplify the expression

More Steps

Evaluate

\frac{2}{21}

To take a root of a fraction,take the root of the numerator and denominator separately

\frac{2}{21}

Multiply by the Conjugate

\frac{2 \times 21}{21 \times 21}

Multiply the numbers

More Steps

Evaluate

2 \times 21

The product of roots with the same index is equal to the root of the product

2 \times 21

Calculate the product

42

\frac{42}{21 \times 21}

When a square root of an expression is multiplied by itself,the result is that expression

\frac{42}{21}

l = \pm \frac{42}{21}

Separate the equation into 2 possible cases

l = \frac{42}{21} l = - \frac{42}{21}

Solution

l_{1} = - \frac{42}{21}, l_{2} = \frac{42}{21}

Alternative Form

l_{1} \approx - 0.308607, l_{2} \approx 0.308607

Show Solution