if a+b=7 and ab=18 ; find a+b
Answers
Answered by
1
Answer:
(a+b)^2 = (a-b)^2 + 4ab
= (7)^2 + 4 (18)
= 49 +72
= 121
(a+b) = sqrt(121)
= 11
Answered by
0
Step-by-step explanation:
a=18/b
a+b=7
18/b+b=7
18+b2=7b
b^2-7b+18=0
b^2+9b-2b+18=0
b(b+9)-2(b+9)=0
(b-2)(b+9)=0
b-2=0 or b+9=0
b=2 or b=-9
ab=18
a×2=18
a=9
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