Question

$if \: a \: + b \: = 5 \: and \: {a}^{2} + {b}^{2} = 13 \: what \: is \: ab$
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Answer 1

$\sf\huge\underline{Answer:}$

Given,

$a + b = 5$

${a}^{2} + {b}^{2} = 13$

${(a + b)}^{2} = {5}^{2}$

${a}^{2} + {b}^{2} + 2ab = 25$

$2ab = 25 - 13$

$2ab = 12$

$ab = 6$

Have a good day!

Answer 2

Answer:

Given

• a + b = 5
• a² + b² = 13

To Find

• ab

Solution

• a² + b² = 13
• ( a + b )² - 2ab = 13
• 5² - 2ab = 13
• 25 - 2ab = 13
• 25 - 13 = 2ab
• 12 = 2ab
• 12/2 = ab
• 6 = ab

Answer = 6