QUADRATIC EQUATIONS
Find two consecutive even integers whose squares
have the sum 340. give solution
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Find two consecutive even integers whose squares have the sum 340.
Let two consecutive positive even integers be 2x, 2x + 2
∴ (2x)2 + (2x + 2)2 = 340
⇒ 4x2 + 4x2 + 4 + 8x = 340
⇒ 8x2 + 8x – 336 = 0
⇒ x2 + x – 42 = 0
⇒ x2 + 7x – 6x – 42 = 0
⇒ x(x + 7) – 6(x + 7) = 0
⇒ (x + 7)(x – 6) = 0
⇒ x + 7 = 0 or x – 6 = 0
⇒ x = - 7 or x = 6
Negative integer is not required, therefore, x = 6.
Hence, integers are 6 × 2, (6 × 2) + 2.
i.e., 12 and 14.
Hope it helps you :]
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