Question
If x1 and x2 are the roots of the equation 2x2
+ 3x – 9 = 0, then the equation which has the roots 1/x1 and1/x2 is:Solution
We know that, for a quadratic equation ax2 + bx + c, Sum of its roots = -b/a and product of roots = c/a For 2x2 + 3x – 9 = 0, => x1 + x2 = -3/2 and x1x2 = -9/2 For the equation whose roots are 1/x1 and 1/x2, Sum of roots = (1/x1) + (1/x2) = (x1 + x2)/x1x2 = -3/-9 = 1/3 Product of roots = 1/(x1x2) = -2/9 ∴ the quadratic equation = x2 - 1/3x - 2/9 = 9x2 - 3x - 2 = 0
1220 ÷ 61 ÷ 5 + 450 of 20% - 70 = √ ?
(42% of 1500 + 170) ÷ 4 = ?2 - 52
What will come in the place of question mark (?) in the given expression?
28 × 15 + 48% of ? = 780
(190/38) × (55/5) + (306/18) = ?
(-251 × 21 × -12) ÷ ? = 158.13
{640 of 8 - (12)2 of 6} - 900 = ?
(1/3) + (2/5) + (3/4) + (11/10) = 3 – (?/12)
360 × 9 ÷ 3 + 120 + 900 ÷ 5 = ?
110 ÷ 5.5 + (?)3 ÷ 12 = 20(2/3)
32 + 26 × (484 ÷ 44) + 450 ÷ 9 = ?
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