Question

expand using formula: (a+7) (a-4)

Answer 1

Answer:

(+7)(−4)

{\color{#c92786}{(a+7)(a-4)}}(a+7)(a−4)

(−4)+7(−4)

{\color{#c92786}{a(a-4)+7(a-4)}}a(a−4)+7(a−4)

2

Distribute

(−4)+7(−4)

{\color{#c92786}{a(a-4)}}+7(a-4)a(a−4)+7(a−4)

2−4+7(−4)

{\color{#c92786}{a^{2}-4a}}+7(a-4)a2−4a+7(a−4)

3

Distribute

2−4+7(−4)

a^{2}-4a+{\color{#c92786}{7(a-4)}}a2−4a+7(a−4)

2−4+7−28

a^{2}-4a+{\color{#c92786}{7a-28}}a2−4a+7a−28

4

Combine like terms

2−4+7−28

a^{2}{\color{#c92786}{-4a}}+{\color{#c92786}{7a}}-28a2−4a+7a−28

2+3−28

a^{2}+{\color{#c92786}{3a}}-28a2+3a−28

Solution

2+3−28

Answer 2

Answer:

(a+7) (a-4)

= a^2-4a+7a-28

= a^2+3a-28