Question

1. If a - b = 4 and a + b = 12, what is the value of a?

Answer 1

I think this is what you are looking for:

=−12

a

b

=

−

12

+=4

a

+

b

=

4

(+)2=42

(

a

+

b

)

2

=

4

2

2+2+2=16

a

2

+

b

2

+

2

a

b

=

16

∴2+2=16+2×12=40

∴

a

2

+

b

2

=

16

+

2

×

12

=

40

Now, (−)2=2+2−2=40+2×12=64

(

a

−

b

)

2

=

a

2

+

b

2

−

2

a

b

=

40

+

2

×

12

=

64

∴(−)=64‾‾‾√=±8

∴

(

a

−

b

)

=

64

=

±

8

So, 2−2=(+)(−)

a

2

−

b

2

=

(

a

+

b

)

(

a

−

b

)

2−2=(4)(±8)=±32

a

2

−

b

2

=

(

4

)

(

±

8

)

=

±

32

Hope that helps and sorry if it is confusing!

Answer 2

Answer:

a=8

b=4

Step-by-step explanation:

8+4=12

8-4=4