Discussion

Evaluate: \(\dfrac{3.8^2 - 1.2^2}{3.8 - 1.2}\)

Answer: D

The numerator is a difference of two squares, so it factorises and the denominator cancels - no squaring is needed at all.

\[ \frac{a^{2}-b^{2}}{a-b} = \frac{(a+b)(a-b)}{a-b} = a+b \]

With \( a = 3.8 \) and \( b = 1.2 \):

\[ \frac{3.8^{2}-1.2^{2}}{3.8-1.2} = 3.8 + 1.2 = 5 \]

Checking the long way: \( 14.44 - 1.44 = 13 \) and \( 13 \div 2.6 = 5 \).

No comment is present. Be the first to comment.

Loading…