Question

Expand 3(t-7)

expand 2t(t-3)
expand -3s(t+5)
expand (3+x) (3-x)
expand (4x-7) (4x+7)​

Answer 1

1) 3(t-7)

= 3t-21

2) 2t(t-3)

= 2t^2-6t

3) -3s(t+5)

= -3st-15s

4) (3+x)(3-x)

= 9-3x+3x-x^2

5) (4x-7)(4x+7)

= 16x^2 -28x+ 28x-49

Answer 2

3t-21

2t²-6t

-3st-15s

9-x²

16x²-49

Explanation:

In general

A(B+C)=AB+AC

(A+B)(D+C)=AD+AC+BD+BC

(A+B)(A-B)=A²+AB-BA-B²=A²-B²