solve the quadratic equations : the difference between two natural number is 4 the sum of their squares is 170. find the numbers.
Answers
Answered by
1
Given
x-y=4 ------->1
(x^2)+(y^2)=170
As we know:-
(a-b)^2=(a^2)-2ab+(b^2)
From this,
(x-y)^2=(x^2)-2xy+(y^2)
(4^2)=(x^2)-2xy+(y^2)
(4^2)=(x^2)+(y^2)-2xy
16=170-2xy
2xy=170-16
2xy=154
xy=154/2
xy=77
Now we know:-
(a+b)^2=(a^2)+2ab+(b^2)
From this,
(x+y)^2=(x^2)+2xy+(y^2)
(x+y)^2=(x^2)+(y^2)+2xy
(x+y)^2=170+(2×77)
(x+y)^2=170+154
(x+y)^2=324
(x+y)=√324
x+y=18 -------->2
From all this two questions we got:-
x-y=4
x+y=18
Add both of this:-
x-y+x+y=4+18
2x=22
x=22/2
x=11
As we know,
x-y=4
11-y=4
y=11-4
y=7
Therefore x=11 and y=7.
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Answered by
39
Answer:
- 7 and 11
Step-by-step explanation:
Given
- Two natural numbers differ by 4
- Sum of their squares is 170
To find
- The numbers
Solution
Let the numbers be (x) and (x + 4)
ATP,
- (x)² + (x + 4)² = 170
- 2x² + 8x -154 = 0
- x² + 4x - 77 = 0
- x(x + 11) - 7(x + 11) = 0
- (x + 11) (x - 7) = 0
- x = -11 or x = 7
(x + 4)² :-
- (a + b)²
- a² + b² + 2ab
- x² + 4² + 2(x)(4)
- x² + 16 + 8x
- x² + x² + 16 + 8x
- 2x² + 16 + 8x = 170
- 2x² + 8x - 154 = 0
x cannot be negative, since x is 7.
Hence, the required numbers are 7 and 11.
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