1. QUADRATICS, P1# - · PDF file1. quadratics,p1#! peipei, page,1,! surds!...
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1. QUADRATICS P1
PEIPEI Page 1
SURDS
RATIONALIZING THE DENOMINATOR
INDICES & EXPONENTIAL
REDUCIBLE
COMPLETING THE SQUARE
INEQUALITIES
NATURE OF ROOTS (DISCRIMINANT)
SIMULTANEOUS EQUATION
SURDS
25 = 5
121 = 11 Rational number
8! = 2
5
17! Surds, Irrational number ( 𝜋, ℮ )
32
Rules:
𝑎 × 𝑏 = 𝑎𝑏 𝑒.𝑔. 3 × 2 = 6
𝑎 ÷ 𝑏 = 𝑎𝑏 𝑒.𝑔. 8 ÷ 6 =
86
1𝑎=
𝑎𝑎 𝑒.𝑔.
32=
32×
22=3 22
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Examples:
a. 54 b. 98 c. 32 − 18 d. 75 + 48 e. 32× 15 ÷ 24 f. 112 − 63 − 28 g. !
!
Rationalize
a. !! d. !! !
!!! !
b. !!! !
c. !! !!! !
Indices
1. am x an = am + n e.g. 75 x 73 = 78 2. am ÷ an = am – n e.g. 96 ÷ 92 = 94 3. (am)n = amn e.g. (23)4 = 212 4. a-m = !
!! e.g. 4-3 = !
!!= !
!"
5. 𝑎!! = 𝑎!! = ( 𝑎! )! e.g. 8
!! = ( 8! )! = 2! = 16
6. a0 = 1
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Examples: Simplify
a. 22 x 24 c. !!!
!!!
b. !"×!!
!!×! d. 3x3y ×4𝑥𝑦!
Examples: Evaluate
a. 16!!!
b. 144! !
c. 27!!
d. (!!)!!
Examples: Solve the following equation
a. 2x = 32 b. 2x = 0.5 c. 24 x 27 = 2x d. 78 ÷ 7x = 49
e. 𝑥!!! = 8
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f. 8! = !!"#
Exponential Equations
If u = 2x then
a. 22x b. 2x + 2 c. 2-‐x d. 4x e. 16-‐x
Reducible to quadratic equations Solving exponential equations
a. 22x – 2x – 2 = 0 c. 16x – 5(22x-‐1) + 1 = 0
b. 3x+1 + 32-‐x – 28 = 0
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1. x4 – 5x2 + 4 = 0 4) 2 𝑥 = 8 − 𝑥
2. x4 – 9x2 – 10 = 0
3. x6 – 9x3 + 8 = 0 5) t -‐ 5 𝑡 − 14 = 0
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Completing the square
ax2 + bx + c = 0
To solve quadratic equation using completing the square method:
a[(𝑥 + !!!)! − ( !
!!)!] + 𝑐
Examples:
a. x2 – 4x d. 2x2 + 6x – 1
b. x2 + 4x + 6 e. 3x2 – x -‐ 7
c. x2 – 6x – 3 f. 5 – 3x – x2
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Solving quadratic equations (Find x) Using completing the square to solve quadratic equations (to find value of x)
Examples:
a. 3x2 – 6x – 1 = 0
b. x2 + 4x – 7 = 0
c. 2x2 – 5x – 1 = 0
Maximum/ minimum values y
f(x) = 2x2 – 4x – 1
= 2[(x – 1)2 – 1 -‐ !! ]
= 2[(x – 1)2 -‐ !! ] x
= 2(x – 1)2 -‐ 3 (1,-‐3)
y = -‐3 (minimum value) stationary/turning point x = 1
minimum value = -‐3 when x = 1. Range is f(x) ≥ −3
1. Given that f(x) = 5 – 3x – x2. Find the minimum value and the value of x.
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2. Find the stationary point of the following quadratic equations
a) y = x2 + 4x
b) y = ( x + 4) (3 – x)
Quadratic Inequalities 1. x2 + x – 2 < 0
(x + 2) ( x – 1) < 0 x = -‐2 and 1
-‐2 1
∴ −2 < 𝑥 < 1
-‐2 < x < 1
2. x2 + 3x + 1 ≥ 0
3. -‐2 + 3x – x2 < 0
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Nature of Roots (x)
x = !!± !!!!!"!!
when you use this formula, 3 results can happen:
1. b2 – 4ac > 0 and you will get two different (distinct) answers for x or two distinct real roots.
2. b2 – 4ac = 0 and you will get the repeated root (i.e. same answer twice). e.g. x2 – 6x + 9 = 0 b2 – 4ac = (-‐6)2 – 4(1)(9) = 0 (x – 3) (x – 3) = 0 x = 3
3. b2 – 4ac < 0 then there are No Real Roots to the equation e.g. x2 + x + 2 = 0
b2 – 4ac = (1)2 – 4 (1)(2) = -‐7 solve using quadratic formula: !!± !!!
not valid
The answers to equations are called the Roots and b2 – 4ac is called the discriminant
b2 – 4ac > 0 is Two Real Distinct Roots
b2 – 4ac = 0 is Equal/same Roots (Repeated roots)
b2 – 4ac < 0 is No Real Root (Complex root)
b2 – 4ac > 0 b2 – 4ac = 0 b2 – 4ac < 0 (Intersect) 2 distinct real roots (Tangent to the curve) (Does not intersect) Equal root/same root No real root/lies above x-‐axis
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Examples: A. Use the discriminant to determine the nature of the roots of the following equations 1. x2 – 6x + 9 = 0 2. 2x2 – 5x + 3 = 0 3. 1 2x
2 + 1 3 𝑥 +14= 0
B. The equation x(x – 2) + k2 = k(2x – 1) is satisfied by two distinct real values of x. Find the range of values of k.
C. Find the set of values of k for which the line y = kx – 4 intersects the curve y = x2 – 2x at two distinct points.
D. The equation of a curve is y = x2 – 3x + 4. Show that the whole of the curve lies above
the x-‐axis.
E. The equation of a curve is xy = 12 and the equation of a line l is 2x + y = k, where k is a constant. Find the set of values of k for which l does not intersect the curve.
F. Find the set of values of k for which the equation 2x2 – 10x + 8 = kx has no real roots.
G. Find the value of constant c for which the line y = 2x + c is a tangent to the curve y2 = 4x.
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H. Find the value of p in each of the following equations given that they have EQUAL ROOTS. i) x2 + (p – 1)x + 64 = 0 ii) 3x2 – (p – 4)x – (2p + 1) = 0
Simultaneous Equations Involving Quadratics 1.
y = 3 – x2 y = 7 – 4x
2. y = 2x – 7 2xy + 3y + 5x + 11 = 0
3. Find the point of intersection between the line y = 3x – 1 and 2y – 5x + 7 = 0 4. The equation of a curve xy = 12 and the equation of a line l is 2x + y = k, where k is a constant. In
the case where k = 11, find the coordinates of the points of intersection of l and the curve. 5. The curve y = 9 – 6/x and the line y + x = 8 intersect at two points. Find the coordinates of the
two points.