Question

2a+3b=7 and ab=2,find 4a^2+9b^2

Answer 1

2a + 3b = 7......(1)

ab = 2........(2)

squaring on both sides in (1) equation

(2a + 3b)^2 = 7^2

=> 4a^2 + 9b^2 + 12ab = 49

=> 4a^2 + 9b^2 = 49 -12ab

put ab = 2

=> 4a^2 + 9b^2. = 49 - 12*2

= 49 - 24

= 25

Answer 2

Step-by-step explanation:

4a^2+9b^2

(2a+3b)^2=(7)^2

(4a)^2+(9b)^2+2(2a)(3b)=49

(4a)^2+(9b)^2+12ab=49

(4a)^2+(9b)^2+24=49

(4a)^2+(9b)^2 =49-24

(4a)^2+(9b^2) = 25