5 Below is a graph of the curve y 4x cosx 10 10T SIX 10 Your friend claims that the slope of the tangent line to the curve at x 4 is the negative of th slope of the tangent line to the curve at x 4 Prove mathematically whether your friend is right or wrong Is the slope of the tangent line to the curve at x a the negative of the slope of the tangent to the curve at x a for any other values of a Explain