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diff --git a/Introduction_To_Linear_Algebra_by_Gilbert_Strang/CH2/EX2.1.1/Ex2.1_1.r b/Introduction_To_Linear_Algebra_by_Gilbert_Strang/CH2/EX2.1.1/Ex2.1_1.r
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+#Example : 1   Chapter : 2.1  Pageno : 37
+#Multiplication by rows and cols dotproduct.
+multiply<-function(A,x){
+  b<-c()
+  for(i in 1:3){
+    b<-c(b,sum(A[i,]*x[,1]))
+  }
+  b<-matrix(b,ncol=1)
+  print(paste("Multiplying matrices by dotproduct of rows and cols"))
+  print(A)
+  print("*")
+  print(x)
+  print("=")
+  print(b)
+}
+
+
+I<-matrix(c(1,0,0,0,1,0,0,0,1),ncol=3,byrow=T)
+x<-matrix(c(4,5,6),ncol=1)
+A=matrix(c(1,1,1,0,0,0,0,0,0),ncol=3)
+multiply(A,x)
+A<-matrix(c(1,0,0,0,1,0,0,0,1),nrow=3,ncol=3,byrow=T)
+multiply(A,x)
+
+
+
+