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diff --git a/60/CH4/EX4.8/ex_8.sce b/60/CH4/EX4.8/ex_8.sce
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+//example 4.1 (pg 149)
+
+     //2x1 + 3x2 - x3 = 5
+    //-2x2 - x3 = -7
+   //-5x3 = -15
+
+A = [2 3 -1;0 -2 -1;0 0 -5]
+b = [5 -7 -15]'
+a=[A b]
+[nA,mA]=size(A)
+n=nA
+
+     //Backward substitution
+
+x(3) = a(n,n+1)/a(n,n);
+
+for i = n-1:-1:1
+	sumk=0;
+	for k=i+1:n
+		sumk=sumk+a(i,k)*x(k);
+	end
+	x(i)=(a(i,n+1)-sumk)/a(i,i); 
+end
+    disp(x)
+\ No newline at end of file