Question

38. If a b=2, ab=11.25, then what is the value of a^2-b^2?
(1) 14
(3) 45
(2) 81
(4) 63​

Answer 1

Answer:

Step-by-step explanation:

a- b=2=>a=2+b

ab=11.25=>(2+b)b=11.25

2b+b^2=11.25

b^2+2b-11.25=0

b^2+4.5b-2.5b-11.25=0

b(b+4.5)-2.5(b+4.5)=0

(b-2.5)+(b+4.5)=0

b-2.5=0 | b+4.5=0

b=2.5 | [b=-4.5 Rejected because root cannot be negative]

So

a-2.5=2

a=4.5

So

a^2*b^2=4.5^2*2.5^2=20.25+6.25=26.50

So 26.50 is answer

I hope it will help you