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9709 P13 - Nov 2019 - Q6 - 7 marks
315

A line has equation \(y = 3kx - 2k\) and a curve has equation \(y = x^2 - kx + 2\), where \(k\) is a constant.

(i) Find the set of values of \(k\) for which the line and curve meet at two distinct points.

(ii) For each of two particular values of \(k\), the line is a tangent to the curve. Show that these two tangents meet on the x-axis.

9709 P11 - Nov 2019 - Q6 - 7 marks
316

A straight line has gradient m and passes through the point (0, -2). Find the two values of m for which the line is a tangent to the curve y = x^2 - 2x + 7 and, for each value of m, find the coordinates of the point where the line touches the curve.

9709 P11 - Jun 2019 - Q2 - 5 marks
318

The line \(4y = x + c\), where \(c\) is a constant, is a tangent to the curve \(y^2 = x + 3\) at the point \(P\) on the curve.

(i) Find the value of \(c\).

(ii) Find the coordinates of \(P\).

9709 P13 - Nov 2018 - Q9 - 8 marks
319

A curve has equation \(y = 2x^2 - 3x + 1\) and a line has equation \(y = kx + k^2\), where \(k\) is a constant.

(i) Show that, for all values of \(k\), the curve and the line meet. [4]

(ii) State the value of \(k\) for which the line is a tangent to the curve and find the coordinates of the point where the line touches the curve. [4]

9709 P12 - Nov 2018 - Q10I - 3 marks
320

The equation of a curve is \(y = 2x + \frac{12}{x}\) and the equation of a line is \(y + x = k\), where \(k\) is a constant.

Find the set of values of \(k\) for which the line does not meet the curve.

9709 P11 - Nov 2018 - Q2 - 4 marks
321

A line has equation \(y = x + 1\) and a curve has equation \(y = x^2 + bx + 5\). Find the set of values of the constant \(b\) for which the line meets the curve.

9709 P12 - Jun 2018 - Q2 - 5 marks
322

The equation of a curve is \(y = x^2 - 6x + k\), where \(k\) is a constant.

(i) Find the set of values of \(k\) for which the whole of the curve lies above the \(x\)-axis.

(ii) Find the value of \(k\) for which the line \(y + 2x = 7\) is a tangent to the curve.

9709 P13 - Nov 2017 - Q2 - 4 marks
323

Find the set of values of a for which the curve \(y = -\frac{2}{x}\) and the straight line \(y = ax + 3a\) meet at two distinct points.

9709 P12 - Mar 2017 - Q1 - 4 marks
324

Find the set of values of k for which the equation \(2x^2 + 3kx + k = 0\) has distinct real roots.

9709 P13 - Nov 2016 - Q1 - 3 marks
325

Find the set of values of k for which the curve y = kx^2 - 3x and the line y = x - k do not meet.

9709 P12 - Nov 2016 - Q3II - 3 marks
326

A curve has equation \(y = 2x^2 - 6x + 5\). Find the value of the constant \(k\) for which the line \(y = 2x + k\) is a tangent to the curve.

9709 P12 - Jun 2016 - Q11II - 3 marks
327

The function \(f\) is defined by \(f : x \mapsto 6x - x^2 - 5\) for \(x \in \mathbb{R}\).

Given that the line \(y = mx + c\) is a tangent to the curve \(y = f(x)\), show that \(4c = m^2 - 12m + 16\).

9709 P11 - Jun 2016 - Q6A - 3 marks
329

Find the values of the constant m for which the line \(y = mx\) is a tangent to the curve \(y = 2x^2 - 4x + 8\).

9709 P13 - Nov 2015 - Q1 - 3 marks
330

A line has equation \(y = 2x - 7\) and a curve has equation \(y = x^2 - 4x + c\), where \(c\) is a constant. Find the set of possible values of \(c\) for which the line does not intersect the curve.

9709 P12 - Jun 2015 - Q11I - 3 marks
331

The function \(f\) is defined by \(f : x \mapsto 2x^2 - 6x + 5\) for \(x \in \mathbb{R}\).

Find the set of values of \(p\) for which the equation \(f(x) = p\) has no real roots.

9709 P11 - Nov 2014 - Q5 - 5 marks
332

Find the set of values of k for which the line \(y = 2x - k\) meets the curve \(y = x^2 + kx - 2\) at two distinct points.

9709 P13 - Jun 2014 - Q8II - 4 marks
333

Find the set of values of k for which the equation \(2x^2 - 10x + 8 = kx\) has no real roots.

9709 P11 - Jun 2014 - Q11I - 3 marks
334

A line has equation \(y = 2x + c\) and a curve has equation \(y = 8 - 2x - x^2\). For the case where the line is a tangent to the curve, find the value of the constant \(c\).

9709 P12 - Jun 2013 - Q3 - 5 marks
335

The straight line \(y = mx + 14\) is a tangent to the curve \(y = \frac{12}{x} + 2\) at the point \(P\). Find the value of the constant \(m\) and the coordinates of \(P\).

9709 P11 - Jun 2013 - Q7II - 5 marks
336

A curve has equation \(y = x^2 - 4x + 4\) and a line has equation \(y = mx\), where \(m\) is a constant.

Find the non-zero value of \(m\) for which the line is a tangent to the curve, and find the coordinates of the point where the tangent touches the curve.

9709 P12 - Nov 2012 - Q4 - 6 marks
337

The line \(y = \frac{x}{k} + k\), where \(k\) is a constant, is a tangent to the curve \(4y = x^2\) at the point \(P\). Find

  1. the value of \(k\),
  2. the coordinates of \(P\).
9709 P13 - Jun 2012 - Q10II - 3 marks
338

Find the set of values of k for which the line 2y + x = k intersects the curve xy = 6 at two distinct points.

9709 P11 - Jun 2012 - Q5II - 2 marks
340

Find the value of k for which y = 6x + k is a tangent to the curve y = 7/√x.

9709 P13 - Nov 2011 - Q7 - 7 marks
341

(i) A straight line passes through the point (2, 0) and has gradient m. Write down the equation of the line.

(ii) Find the two values of m for which the line is a tangent to the curve \(y = x^2 - 4x + 5\). For each value of m, find the coordinates of the point where the line touches the curve.

9709 P12 - Nov 2011 - Q4II - 3 marks
342

The equation of a curve is \(y^2 + 2x = 13\) and the equation of a line is \(2y + x = k\), where \(k\) is a constant. Find the value of \(k\) for which the line is a tangent to the curve.

9709 P11 - Nov 2011 - Q9II - 4 marks
343

A line has equation \(y = kx + 6\) and a curve has equation \(y = x^2 + 3x + 2k\), where \(k\) is a constant. Find the two values of \(k\) for which the line is a tangent to the curve.

9709 P13 - Jun 2011 - Q2 - 5 marks
344

Find the set of values of m for which the line \(y = mx + 4\) intersects the curve \(y = 3x^2 - 4x + 7\) at two distinct points.

9709 P12 - Jun 2011 - Q3 - 5 marks
345

The equation \(x^2 + px + q = 0\), where \(p\) and \(q\) are constants, has roots \(-3\) and \(5\).

(i) Find the values of \(p\) and \(q\).

(ii) Using these values of \(p\) and \(q\), find the value of the constant \(r\) for which the equation \(x^2 + px + q + r = 0\) has equal roots.

9709 P12 - Nov 2010 - Q6 - 7 marks
346

A curve has equation \(y = kx^2 + 1\) and a line has equation \(y = kx\), where \(k\) is a non-zero constant.

(i) Find the set of values of \(k\) for which the curve and the line have no common points. [3]

(ii) State the value of \(k\) for which the line is a tangent to the curve and, for this case, find the coordinates of the point where the line touches the curve. [4]

9709 P11 - Nov 2010 - Q11III - 4 marks
347

The equation of a curve is \(y = \frac{9}{2-x}\).

Find the set of values of \(k\) for which the line \(y = x + k\) intersects the curve at two distinct points.

9709 P13 - Jun 2010 - Q10I - 4 marks
348

The function \(f : x \mapsto 2x^2 - 8x + 14\) is defined for \(x \in \mathbb{R}\). Find the values of the constant \(k\) for which the line \(y + kx = 12\) is a tangent to the curve \(y = f(x)\).

9709 P12 - Nov 2009 - Q10II - 4 marks
349

Determine the set of values of k for which the line 2y = x + k does not intersect the curve \(y = x^2 - 4x + 7\).

9709 P1 - Jun 2009 - Q2 - 4 marks
351

Find the set of values of k for which the line \(y = kx - 4\) intersects the curve \(y = x^2 - 2x\) at two distinct points.

9709 P1 - Nov 2007 - Q1
352

Determine the set of values of the constant k for which the line y = 4x + k does not intersect the curve y = x2.

9709 P1 - Jun 2021 - Q1
353

Find the value of the constant c for which the line y = 2x + c is a tangent to the curve y2 = 4x.

9709 P1 - Nov 2005 - Q9
354

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.

9709 P15 - Jun 2026 - Q6 - 4 marks
9072

Find the set of \(k\) for which \(y+4x=k\) and \(y=4-7x-2x^2\) have at least one intersection. [4]

9709 P11 - Nov 2025 - Q1 - 4 marks
9633

Find the set of values of \(k\) for which the quadratic equation \[3kx^2+(k+8)x+3=0\] has two distinct real roots. [4]

9709 P12 - Mar 2021 - Q2 - 4 marks
10401

By using a suitable substitution, solve the equation \[(2x-3)^2-\frac4{(2x-3)^2}-3=0.\]

Find the real solutions. [4]

Two roots are not always two positive roots · Maths4U Original · 8 marks
16777

Notes & worked examples

Info
Maths4U Original · M4U-ORIG-QUAD-005

For a real parameter \(p\), consider \(x^2-2px+p+6=0\).

  1. Find all \(p\) for which the equation has two distinct real roots. [3]
  2. Find each value of \(p\) that gives a repeated root, and state that root. [2]
  3. Find all \(p\) for which the equation has two distinct positive roots. Justify your answer. [3]
Two tangents through a fixed point · Maths4U Original · 8 marks
16778

Notes & worked examples

Info
Maths4U Original · M4U-ORIG-QUAD-006

The curve is \(y=x^2+2x+4\). A line through \((0,1)\) has equation \(y=mx+1\).

  1. Show that an intersection has x-coordinate satisfying \(x^2+(2-m)x+3=0\). [2]
  2. Find both values of \(m\) for which the line is tangent. [3]
  3. Find the point of contact for each gradient. [3]
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