Question

Evaluate: a. [6ab (a^2 + 9a + 20)]

b. [ 5x^2 + 35x + 60]​

Answer 1

Explanation

a. [6ab (a² + 9a + 20)]

$\colon\implies{\sf{ 6ab (a^2 + 9a + 20) }} \\ \\ \\ \colon\implies{\sf{ 6ab[ a^2 +(5+4)a+20] }} \\ \\ \\ \colon\implies{\sf{6ab[ a^2 + 5a + 4a + 20 ] }} \\ \\ \\ \colon\implies{\sf{ 6ab[ a(a+5)+4(a+5)] }} \\ \\ \\ \colon\implies{\sf{ 6ab[ (a+5)(a+4)] }} \\ \\ \\ \colon\implies{\sf{ 6ab (a+5)(a+4) }}$

b. [ 5x² + 35x + 60]

$\colon\implies{\sf{ x^2+7x+12}} \\ \\ \\ \colon\implies{\sf{ x^2+(4+3)x+12 }} \\ \\ \\ \colon\implies{\sf{ x^2+4x+3x+12 }} \\ \\ \\ \colon\implies{\sf{ x(x+4)+3(x+4) }} \\ \\ \\ \colon\implies{\sf{ (x+4)(x+3) }}$

More to Know

• (a+b)² = a² + b² + 2ab
• (a-b)² = a² + b² - 2ab
• a²-b² = (a-b)(a+b)