Step 1: Determine the roots of 3x2−5x−7=0 from the graph.
The roots of the equation 3x2−5x−7=0 are the x-intercepts of the graph y=3x2−5x−7, which are the points where the curve crosses the x-axis (where y=0).
From the graph, the curve crosses the x-axis at approximately x=−0.9 and x=2.6.
a) (i) The roots are x=−0.9andx=2.6.
Step 2: Determine the minimum value of y from the graph.
The minimum value of y for this parabola (which opens upwards) is at its vertex, the lowest point on the curve.
From the graph, the lowest point on the curve is at y=−9.
a) (ii) The minimum value of y is y=−9.
Step 3: Calculate the gradient of the curve at point x=2.
To find the gradient of the curve at x=2 from the graph, we need to find the gradient of the tangent line to the curve at x=2. The image provides a calculation using two points on what appears to be a tangent line or a secant line approximating the tangent. The points used are (x1,y1)=(1.30,−10) and (x2,y2)=(3,1.5).
The formula for the gradient (slope) is:
m=ΔxΔy=x2−x1y2−y1
Substitute the given points:
m=3−1.301.5−(−10)
m=1.701.5+10
m=1.7011.5
m≈6.7647
Rounding to one decimal place, the gradient is 6.8.
a) (iii) The gradient of the curve at point x=2 is ≈6.8.